If we've learned anything about Universal's parks mentality over the past, say, 15 years, it's that they are not in any way nostalgic for their own park's history, they will replace anything at any time under circumstances they deem necessary, and they don't care at all how attached some of us in the fan community are to the attractions that turned us into Universal parks fans in the first place.
I don't think there's much sacred to them at this point, and while that has a positive effect on keeping the parks always fresh(ish), I think there's a better balance that could have been struck over the years.
There's definitely a little something to this. I can't think of the last time I saw E.T. playing on television, even on networks owned by the parent company. Perhaps this has something to do with Spielberg not wanting it to be in constant rotation so that the few times it does pop up feel more like "events." I can't think of another explanation for why Universal hasn't done more to keep it more in the (general) public's mindset, because it's a masterpiece and was the highest-grossing movie of all time for many years. It's not like it was some obscure little art film.