An interesting topic.
People seem to want a protagonist who is either relatable or admirable. Unfortunately, what is relatable or admirable differs from person to person and worse, they seem to have forgotten all about the relatable part most of the time. Also unfortunately, the industry seems to have taken 'admirable' to mean extremely sexualised (macho men, effeminate teens, voluptuous women,) callous and deadly.
There are very few games out there which allow you to play as a relatively normal person thrust into circumstances that force them to become something different. Those games do stand out, such as the Fallout series, which I personally find far more involving. Most games go for simple character archetypes, which is great for admirability and/or style, horrible for relatability and/or immersion.
On the other hand though, it really does depend upon the game. If I'm playing the game equivalent of Commando (the old Arnie film) it would only make sense to play as a human hamburger. If a game has any pretense of any depth of plot however, all your Master Chiefs and so on tend to hinder rather than help the experience.
Though I guess at the end of the day, if a character isn't at all relatable, they might as well be good to look at. More effeminate males and muscular females please... that's how this Geordie lad rolls. z: )
Finally, I particularly sympathise with the comments regarding equipment and attire. Ridiculous costumes and weapons are fun in their own way, but there just aren't enough games that go the sensible route. I'm afraid I have to lump the main character from the first Assassin's Creed in here... it did kind of bug me that you were playing a stealthy assassin whose every slightest movement was accompanied by the creak of leather and the jingle of sharp shiny metal.
HERE'S THE BIT I HOPE YAHTZEE CASTS HIS EYES UPON:
I fully support Space Game the Game. Speaking as a disabused space-sim player (my freaking joystick has gathered freaking dust) I'd love to see even one more decent game come out, though I hope you will look after the fluff. The sci-fi technical fluff is important you know.
Stuff quickly freezing really isn't all that likely to happen in space. Space is a vacuum. There's nothing to conduct the heat away. In fact, by all accounts, one of the biggest forseeable problems with spaceship construction is preventing the damn thing from overheating. Not that this is a big problem for the system proposed - you just make mention that the cooling system is f**ked and is always on full blast.
I just hope you mention something like that. Otherwise you'll have a bajillion geeks squealing at you with the voices of tortured rats. In your soul at night.