When Israel crossed into the Sinai, having beaten or signed armistices with all the Arab states but Egypt, the RAF started strafing them so moves in to Egyptian territory can only end badly while Gaza equals a tiny piece of land and a massive increase in the number of Arabs in Israel.
More importantly is that Israel did as well as it did because of Arab disunity and particularly the bad blood between Abdullah and Farouk, which enabled Israel to avoid too much time on a multi-front war. An effort to seize the West Bank, in violation of tacit agreements between Israel and Jordan, will have a double cost to Israel:
1) Israel will be forced to come up with sufficient military forces to launch a successful offensive campaign against a highly professional military with the goal of crushing that military, an army Israel did NOT defeat in this war OTL. No review of IDF strength 1948-49 shows large reserves of troops not in use and even less so in terms of armor, aircraft or artillery.
2) To do this Israel must not only find the men and material to fight and defeat Jordan but to hold off the Egyptians. Incidentally, if you call up a map of Israel look at Beersheba. Egypt held that town and everything save a few besieged villages to the south at the time a choice between the West Bank and the Negev was being made.
That's a lot of Israel territory today.
Then there's the British-Jordanian alliance issue...