There's lots to improve on. To be honest, most games these days are really shallow and there's lots of interactions we just flat-out haven't explored. People talk about whether or not games used to be better or whether they look through nostalgia goggles, but there's a handful of cases where we geniunely did have deeper interaction before the current console generation. To give you an idea...
Mass Effect vs. Baldur's Gate:
Yes, Mass Effect is prettier and has physics and voice acting, but Baldur's Gate has deeper interactions. Just as one example, there's one way to open locks in Mass Effect, and that's hacking them--and occasionally to find a keycard. In Baldur's Gate you can have someone pick the lock, you can try to force it open, you may have a number of spells at your disposal for magically unlocking them, and you can almost always count on a key being hidden somewhere. In Mass Effect you either have enough hackers around to open the door or you don't. Solution: go back to the ship, grab another tecchie, and go back. In Baldur's Gate you have resources at your disposal and must choose how to best employ them. Is it worth using the Knock spell on this lock or that lock? Is it worth taking the time to find that key? This is one example of how Baldur's Gate's really simple user interface was a lot more versatile and bred a lot more creative thinking on the player's part. It seems that since Knights of the Old Republic Bioware's been confining themselves into a smaller and smaller box, depending on a checklist of "standard Bioware features" more than anything else.
Dungeon Keeper:
An innovative and unique game where it was good to be bad. Players took on the role of the eponymous Dungeon Keeper, who, from the Dungeon Heart, commanded imps to dig tunnels and built rooms for storing gold, training demons, feeding them, torturing and imprisoning heroes, and more. Your dungeon served a dual-purpose as you built it to attract more fiends, managed your minions to keep them from fighting or hogging too many resources to themselves, and fortified it against impending invasion by the heroes. In addition to managing the denizens of your dungeon you could put them to work, having imps mine gold and jewels from the rock and soil around your dungeon and putting dark wizards to work researching spells for you to use. It's difficult to describe this game as anything other than "Dungeon Keeper," but if I had to pick some games it plays like I'd say it's like a combination of Viva Pinata and Black and White--and that doesn't really do it justice. Few--possibly even NO games since its time--have even approached its versatility, and you'd be surprised at how many senses of pleasure it speaks to. On one hand, you got to manage evil minions in a game somewhere halfway between an RTS and a demented hotel simulator of some kind, with the demons actually having their own behavior and social infrastructure--certain monsters hate certain other demons and you have to keep them from fighting, and different monsters tend to like doing certain things and fight harder if you can keep them happy. On the other, you got the pleasure of building and even exploring, with hidden passages and forgotten temples lying in unexplored portions of each level. If you can point me at a modern game that can give me the depth of the Dungeon Keeper games, I'll be surprised.
Believe me, games today have LOTS of catching up to do. It says a lot that most gamers could STILL imagine a better Bioshock than what the developers actually came up with...