To continue this theme of hollow characters, I'd like to do a little thought exercise. I think you should try it too, because it's fun.
Picture one of the games you've played recently that had a hollow or window main character. Now replace them with a very strongly NON-hollow character. Imagine how the game would feel differently and then imagine how, if the game was designed with that character in mind from the start, how it might be fundamentally different.
For example, replace Mass Effect's "Shepard" with, say, Captain Kirk. This one's easy.
In most regards, Kirk is easy to picture in Shepard's shoes. It's not much of a stretch to see Kirk going to war like that, although it's not exactly what he would do in Trek. I can't see Kirk driving around on barren planets looking for mineral deposits and loot, but I couldn't see Shepard doing that, either.
From a plot perspective, Kirk fits fine into the role of the young renegade captain sent on a special mission with a special ship. However, all the interpersonal aspects of the plot will screw up a bit because Kirk's character doesn't really have those dynamics. His romances are always held at arm's length, for example.
The whole idea of "choosing noble or asshole" is still viable, but it would be done in true Kirkian style instead of mushy, wishy-washy hollow character. "Garrus... you can't... go around killing people!" "It's Wrex - he's gone out of... control!"
The fact that Kirk actually has a personality lets the writing justify letting Kirk take the lead more often, whereas Shepard is ENTIRELY a reactive character. This is because writing an active role for a hollow character results in the players feeling like they've been gypped out of the options they would really like... but that problem is much reduced if the main character has such a strong personality that the player can't deny that the options are all that make sense for him.
If the game was designed with Kirk in mind from the start, I think it would feature the ship more centrally, because Kirk is a captain above all. Sure, he gets in fist fights and fires lasers and boffs a space elf, but the whole purpose of his character is to be the beating heart of his ship.
This sort of character replacement is kind of a fun exercise. That example was pretty straight - a substitution of a bland character with a very similar non-bland character. But it's often fun to imagine really zany mixups, and we can still claim it's educational so long as we think about how it would actually change the game.
For example, imagine Mirror's Edge with Raz from Psychonauts as the main character.
Or imagine Ash from Evil Dead as the main character in Crackdown. (Or Ash from Pokemon, I suppose.)
Or imagine Shodan as the "main character" in SimCity. Go nuts.
The point isn't "How would these characters fit into the game?" The point is "How would the game change to fit in these characters?"
I especially like that SimCity one. Imagine a city-building game where you play an evil artificial intelligence. Ha! "The only thinggggs of beauty in the dirt you call a citttyyyy... are the thiinnnnggggss IIIiiii builllllt therrrrrre."