Are Germans today seething that they lost Kaliningrad Oblast? The Germans recognise that Russia was so much bigger then them, that there was nothing they could do. The problem in the M.E. as far as Israel is concerned is because she is so small, the Arabs feel that they can do something about it.
While I appreciate the point you're trying to make,
these two things are NOTHING alike.
1) Germany kind of started the whole mess, and it's been drilled into their children and grandchildren that "German Nationalism = Bad". Perhaps a bit overly so. But there was an eventual acceptance that while much of old Germany was lost, there is still plenty of it left.
By contrast, the Palestinians effectively lost
their entire country to foreigners. They eventually got Gaza and the West Bank back, but even then, these are dotted with Israeli settlements and security checkpoints (not to mention the infamous 10' concrete wall in Gaza) that people feel they haven't really gained any of it back.
2) While the Germans in former Prussian territory were forcibly evicted by Soviet, Polish, and Czech authorities post-war, they still had the territory of modern day Germany (or East and West Germany back then) to resettle, recover, and eventually their great-grandchildren accepted the loss and moved on with their lives - because they have something worth living for.
The Palestinians never had that. The Palestinian diaspora carried the weight of the lost homeland around with it as part of its cultural identity, and while many eventually settled down in decent social and economic positions in many countries, most Palestinians never did. The majority of Palestinian refugees from the 1948 and 1967 wars were forced to live in temporary refugee camps that had to become long-term population center. Many of these 'refugee camps' are now urban centers similar to Detroit at its worst times, particularly those in Lebanon (where the Palestinians were never truly accepted) and some in Jordan (which took the bulk of these refugees). The countries housing these people never truly accepted them, or still has considerable ethnic tensions regarding them. Jordan, which reportedly has anywhere between 40 to 60% of its population as of Palestinian origin, still has problems with the Palestinian-Jordanian divide, with the latter feeling they've been forced to accept foreigners onto their land, and the Palestinians sometimes feeling unwanted despite knowing there's really no other place for them now. Palestinians may become captains of industry and business in Jordan, but the problems are still there. The Syrians treated their refugees slightly better, but everyone knows it's mostly for propaganda purposes and to create people willing to fight Israel for them in the long run.
The 1990s peace talks were supposed to give the Palestinians a homeland at long last, something to call their own. And yet even after two decades, every step forwards seems to be matched by another step back. Much of the Palestinian lands are still under Israeli control. They don't have control of their borders, they're under constant pressure to kowtow by Israel on security issues, and they don't have much in terms of resources. The PLO proved a corrupt administrator. Many feel noting has been gained, which is why HAMAS won elections in Gaza and the Palestinians becoming more and more disgruntled about a peace "that has given us nothing". And things keep on going.
The Germans, for however screwed they got after WW2, were at least given a chance to recover, rest, and move on. The majority of Palestinians keep getting shafted, and so they could do nothing but seethe in anger for decades.