More hairstyles seems to be popular. Add one more vote for that, please.
Regarding the Mako: see a game made about 10 years ago called Recoil by Zipper Interactive (EA). They nailed fast and furious tank combat. Battlezone by Activision wasn't so bad for hover tank gameplay either. Hmm... <goes rummaging for discs> Real time strategic base building might be a bit much for the target audience of the ME series, but I'd welcome it.
More, more, and many more options for dealing with situations and people. Writers need to eat too! Give 'em work!
NPCs - more AI and no unlimited ammo.
Puzzle games need revisiting. No scooping the cat box (planet scanning), please. I'd really rather have to do missions and/or use my influence to gain upgrades to powers, ships, weapons, and armor. Let someone else like the Alliance or Cerberus foot the bill, since they have the resources. Shepard is a warrior, not a prospector. She could be a scavenger though... hmm...
Please, please, please - kill the George Lucas/Blizzard madness affecting the marketing department when it comes to having to purchase tons of high fructose corn syrup products just to get some neat looking gear. It also sucks to find that I pre-ordered my game from the "wrong" place and got the shaft when it came to in-game perks. Everyone should get an option to choose one or more perk(s) for being so confident in Bioware's product that they Pre-ordered it.
Random encounters with NPCs that offer upgrades that not every character will find would go a long way toward replay value.
I'd love to be able to turn helmets off - even with the bonus Cerberus/DA:O/CE armors.
You can take sex out of the game if you promise me some actual romance. Love is full of uncertainty, certainty, hope, fear, longing and yeah; sex. It'd mean more if you'd make Shepard work for it, not just wait for it.
Downloadable content is seldom worth the cost, in my experience. Please lower the prices about twenty to fifty percent, depending on length and reuse of assets. Bethsoft put out free DLC at one time, then made awe-inspiring expansions. When they started overcharging for their near-worthless DLC for Oblivion and then Fallout (expansions notwithstanding), I stopped buying, and then stopped playing, having become disillusioned. NWN left me with the same bad feeling, but at least it wasn't horse armor! The alternate clothing pack fits that description, though.
Here's an idea: contract the community people who have proven to make the best content for your games, so that they have another reason to keep at it, you get to sell it, and people have more and more diverse content than they know what to do with. Let us pay what we can afford. I think you'd be surprised just how popular that would be and how lucrative. I'd love to support the many mod makers that keep me playing games well beyond the original content. ME doesn't have mods, I know, but you may have a toolset available for ME3 that would affect the whole trilogy. It could happen. 8)
Do away with EA points as the only option to buy from you. We already have one system of worthless fiat currency. Why on earth do we need another one appended to it?
Even with all I'd like to see improved over what's been sold to us, I still have to say that it was a damn good purchase. I'm still loving it, with only starry-eyed anticipation in my heart. Keep up the fine work.
P.S. For the PC, please consider letting us save when there are no enemies nearby, as opposed to saving when no enemies know we're there. Saving anytime would be even better.