False. Your confusion lies in the fact that you believe this will do good for the Cuban people, as if somehow magically a place with no free market and a government that has historically given it's people dirt will all of a sudden benefit from these relations. This money will go to the Cuban communist regime, not the people that are suffering that need it. That is where there is truly no logic and severely detached from reality.
Even if 1% of that money gets to the people (and, pragmatically speaking, more of it will for sure), then they are going to be better off.
More importantly, if it prompts economic reforms along the lines of what most other communist countries did - the closest example here probably being Vietnam - the people are going to be vastly better off even if the authoritarian political system remains in place.
Either way, while we can only guess what will happen without sanctions, we know full well what happens with the sanctions: absolutely nothing. So what exactly is their purpose then?
Also, even if it was for revenge, would you really blame someone who feels that way?
Blame them for feeling that way, no (well, it depends on who they were before Castro; if it's one of Batista's cronies, or the members of the top ruling elite supporting him, I'd say they can suck it and go cry in a corner; I have no sympathy for people robbing others under gunpoint when they get robbed themselves in a similar fashion). But I will blame them for letting that emotion guide their political decisions, and especially for pushing the same onto others.
Oh, as for my comfy chair. I was born in a communist country. Don't try that "you rich American asshole can't understand" on me.