I’m not sure I follow that idea that TFA “ignored” the prequels. The way I see it is that it just didn’t come up. The prequel timeframe is now 2 generations removed from Rey and Finn, so it’s feasible that most of those events are pushed aside from memory in favor of more recent events (like what happened in the OT). In the movie, stuff from the OT is already just rumors and tall stories. And that was "only" 30 years prior. So what would events from 50+ years prior be like? Likewise the Clone Wars and those events were already half forgotten during the OT as well, stuff or legends and wild stories, to Luke at least.
So like I said, it just didn’t really come up.
Maybe JJ and company didn’t make an effort to sneak some prequel stuff in there, I’ll give you that. But then that would be just as forced as Finn finding the training ball or turning on the dejarik table and wouldn’t serve anything at all to the audience or the story. At least the callbacks to the OT were to incite nostalgia (although I think it was unnecessary) in us old timers. Do the prequel-ers need nostalgia from 15 years ago?
From Disney's perspective, I'm sure they simply wanted to play it safe. Why make references to a trilogy that was maligned and controversial for so long?
And TFA really was a love letter to the OT, in essence remaking it.