I don't think high expectations are out of bounds today. I think if you have a Windows game it should cater to Windows architecture and not console architecture; if you have to dumb down your game to the lowest common platform then people on the better platforms will feel like you're putting blinders and weights on them Harrison Bergeron-style.
Specifically, take Deus Ex 1. The opening level of Ellis Island was huge, with an interior to the Statue of Liberty. I believe the vault underneath which held UNATCO HQ was a separate load area but it might not have been.
Then we have DX2, which *spoilers* but whatever it sucked go play something else if you haven't ... in DX2 the end level was Ellis Island surrounded by sight-blocking ice walls which split the level into three or four parts - and the island was smaller besides, and lacked a statue interior.
I'd say, make the game as rich and complex and make the working parts of the game as grand and cool as you did before. At least. It's not ok to dumb it down. But the platforms we have now are faster and stronger, so you can have a grander game. With that extra you can choose to put it into graphics so it doesn't look like we're playing something from 2000. Or you can use the extra to make the game grander and tell the graphics to shove it.
What is not ok is using all that extra power for graphics, and then eroding the gameplay to make more room for graphics. While that may make the game more accessible to casual gamers, it destroys the game for anyone who played the first one and grew accustomed to its greatness. DX3 managed to walk that line and delivered better on gameplay than DX2 did, without compromising graphics too much. I personally feel that they could have shafted graphics processing more than they did.
This service to casual gamers is, I believe, a disservice. Through hardship we test and know our limits, through adversity we grow. If the games available to you are all casual, you will never develop higher quality gaming skills and more refined tastes. Give the casual gamer an Easy mode, rename it Normal so they don't feel pissed upon, but leave in the Hard for the grognards and Impossible for the masochists. And leave players to decide whether they want a game where each texture is high resolution and has six layers of processing filters, or a world 4x as vast and rich which looks goddamned good enough.