Ah, yes, the Master Chief effect. The same thing can be said of side boob and panty shots being somehow hotter than straight up nudity. It's the mystery that keeps it so very interesting and enticing because what we can come up with in our own individual imaginations is far superior to what BioWare could ever present us.
On the other hand, every mystery novel has an ending and I'm presuming that this game will wrap up the Reaper invasion if not the entire Mass Effect series in general. It's conversely very understandable in the Halo series for MC to keep his hat on when in front of the camera because they'll presumably keep making Halo games indefinitely at the present time and why not? They make money, so no reason to spoil MC's real face anytime soon and really, I can already guess what he looks like. Short, dark hair. Clean face. Super generic. And even though I read the first Halo book I can't actually remember how they described his appearance... But I'm getting off track.
All in all, as Mass Effect 3 draws to a close it should wrap up many things. They've already revealed what Krogan females look and sound like which is itself a huge thing. In fact, aside from humans and the "genderless" Asari, we've never seen another race's womenfolk. Hopefully we'll get to see them as well, plus a logical reason as to why they've been so camera shy (I know they explained why Krogan females are hidden away, but Garrus has specifically said he had a "friendly brawl" with a female Turian soldier soooo...). Quarians as an entire race have been in the shadows and in the end I think it'd be nice icing on the cake to finally see Tali's face.
Additionally, the devs shouldn't be so worried about what she'll look like if they do reveal her. Sure, we all have our expectations and our own ideas as to what's behind the mask, but in the end, it's THEIR IP. THEY made it. If they say Tali looks hideous, for whatever reason, we all just have to deal.
Regardless, the games so far have been kinda hit and miss with the combat and the RPG aspect, but at least we can all rest assured that the story will be well told... so long as they don't take the Dragon Age 2 approach to it.
inb4thatoldarguementstartsupagain