A secondary concern is a voting block in the US.

I suspect that is primary. Jewish persons control a lot of wealth in this country. So they wield an out-sized amount of power compared to their population. At this point, I don't think there is any guilt about the genocide. It has almost passed out of living memory (just a few people who remember). It's a matter of history now.

We did (and do) pay lip-service to "democracy". During the Cold War, being anti-communist was more important (IMO, wrongly). So we put up with a lot of dictators.

I think Israel is useful in that they can whack their neighbors while we stand back and watch. Sometimes we say "tsk tsk". But we don't get our hands dirty. A cynical view, but I think reasonably accurate. That they are a democracy makes it easier to justify supporting them.

Also, I believe just off their coast is a significant amount of gas. No oil, but if Israel could get hold of that gas, that would be a good source of revenue.