First thing's first: Likud was just as scornful, if not more, of the Mizrahim as Avoda. The difference was that Likud never held any power until the late 70s, by which time they'd already managed to cast themselves as "defenders of the underdogs". I've noted on this board before that I strongly believe that an earlier Revisionist government would have treated Mizrahim as badly or worse than OTL's Mapai. That said, the Israel right lost earlier that fiercely secular, at times anti-religious edge that characterized the early Israeli left; since Mizrahim were and still are more religious on average than Ashkenazim in Israel, that's probably driven at least some of them away.
[QUOTE="Alon, post: 12600701, member: 77891"and the kibbutzes treated them like savages.[/quote]
Please, tell us how you really feel.
Now, I can't speak to how the kibbutzim treated the Yemenites (frankly, I doubt they had much to do with each other since the early Yemenites tended to settle near Jerusalem while the kibbutzim preferred the Galilee), but I do know that Yemenites were a substantial faction at Bezalel, an Ashkenazi-founded and dominated establishment closely associated with the Zionist mainstream. These Yemenites were largely respected and treated as equals, though there does seem to have been at least a little Orientalism involved in the adoption of their styles by Ashkenazi artists.
The Russians are a different matter. They're associated with the right nowadays, but they voted for Rabin in 1992 and for Barak (though not Labor) in 1999. They associate socialism with Soviet failures, but they do have certain social demands, such as public housing, which Labor has ignored. Lieberman knew how to appeal to them, but his reputation in the community has been declining since 2013, and his base is now reduced to older first-generation immigrants who often speak little to no Hebrew; the 1.5th and second generations have more political diversity, and the more right-wing among them vote for Likud or Jewish Home. It's more correct to identify the Russians as a bellwether group, even if they're somewhat right-wing on average. Don't forget, Jewish Israel is generally a right-wing nation; at 50/50 equilibrium, or rather 60/60 in the Knesset, Jews vote 60-45 for right-wing parties, and the remaining 15 left seats are from Arabs.
I think the main issue is that the Russians are largely very hard-line on defense. Once not very long ago, the Israeli mainstream left (that is, Avoda and not Meretz or, heaven forfend, Maki, which operates in Israel more as an Arab party than a Leftist one) were basically just as hardline as the mainstream right (Likud) on defense. The mid-90s saw the shift towards Avoda being more "Peace-y", which lost them a lot of Russians.
But as for the Mizrahi population, the major waves of them came in the 1950s, and were subjected to pretty dehumanizing conditions in the tent cities, along with the mockery of their religious views. That permeated into support down the line for whoever opposed those in charge.
It should be noted that there were also Ashkenazim in the ma'abarot, and the State of Israel frankly did the best they could considering that they were absorbing more than their population in refugees over less than a decade. That said, there certainly was a lot of discrimination that was almost certainly racist, though not always overtly so. For example, one of the arguments given to the preferential placement in towns that was given to Ashkenazi ma'abara residents over Mizrahim was that they had better "usable skills" or whatnot, which was often colored by racist/colonialist/whatever disregard for Arab culture, because obviously a Polish woodworker is much better trained than a Moroccan one. But I do think in general that the shittiness of the ma'abarot was exaggerated by politicians looking to rally easy support. The fact of the matter is that Israel was heavily strained with all of those refugees, and honestly did their best at feeding and providing services to people, a task complicated by the fact that it was a newborn country, quite poor, engaged in low-scale warfare with its neighbors.
A different matter is the systematic preference that was exhibited by the government through the 50s and 60s and 70s (and in many ways, through today) to Ashkenazi-majority towns and regions over Mizrahi-majority ones, plus Mapai's special favoritism for the (mostly Ashkenazi) kibbutzim.
If Herut was in charge, somehow, and similar conditions occurred, which just might have happened, would that manifest into support for Mapai? While Begin was eager to court Mizrahi votes and act as a spokesmen for their community, other Revisionist Right Wing Ashkenazi politicians did not hold similar views at all. How do you get Herut into power in the 50s?
If Herut had been in charge, I imagine that absolutely nothing would have gone significantly differently with regards to refugees and cultural disrespect (Herut was, of course, also an entirely Ashkenazi game, and classic Revisionist Zionist was just as secular as Labor Zionism); if anything, I would expect that Herut's history of fascism to lead them to have stronger opinions about race. But...getting Herut into power in the 50s is basically impossible, I think. Labor had a big advantage in numbers and especially in organization. Labor could say with a straight face that the IDF was basically the Palmach and that it was basically Mapai that established Israel and won independence - and things the Altalena Affair and the Sergeants Affair makes it fairly easy for Mapai to paint the right as potentially traitorous.
Getting a right-wing government in the 50s would, in my opinion, require going back at least to the 30s, though probably even further. The main problem is that Labor Zionism, with its strong emphasis on "redemption of the soil" and ideas about Jews becoming proletariat has a stronger migratory effect than Revisionist Zionism, which is more about Jews sticking up for themselves and not being weak. Betar was very popular in the Baltics and Poland, with numbers similar to haShomer haTzair, but they were less successful at getting people to emigrate. Add to that the fact that all of the Yekkim from the 5th Aliyah had valid reason to be very wary of fascism (Irgun was openly fascist, like wearing-brown-shirts-and-having-conferences-with-Italians openly fascist, and Lehi was almost as bad on that front), and a strong Israeli right wing is a non-started until all of the DPs and Mizrahim started getting organized enough to vote. Changing that would require fundamentally changing the nature of Zionism basically from Herzl's death.
EDIT FOR NINJA'ING
I think that's what most people think, and until a few years I thought the same, but anti-Mizrahi discrimination in Israel foes further back, to early Zionism. The people who backed the early Zionist projects were European racists. One, Arthur Ruppin, was deeply influenced by romantic German nationalism, and viewed the European Jews as a Germanic race that had a small Semitic cultural component that could and should be extinguished.
I would really, really love some backup for this, because I have never heard anything like this. In fact, as good socialists, I would expect most of the Zionists to be less racist than the average European. And Arthur Ruppin was one of the founders of Brit Shalom!