If you want to play an alien there is always multiplayer for you and that's fine because the MP is very good.
Eh. I do really like multiplayer, but ME3 and DA:I's MP is a very small experience compared to their single player campaigns. You just get to fight stuff, really, and you don't get to really choose much about your ME3 MP character besides the color of their gear and how you're going to specialize their very small power lists. You don't get to customize the way they look independant of their armor, you don't get to talk to people, experience a plot, make choices, or explore non-combat areas. And depending on which alien you want to place as, you could have a very limited class selection, so if I wanted to play a female Quarian Soldier, for example, I'm out of luck. For those reasons I don't really feel like I'm actually playing an alien in ME3's multiplayer. If anything it almost feels like a demo for what could be.
Personally I'm very hopeful about the possibility of playing as an alien in the next Mass Effect. And yes, I do know to temper my expectations because it is a lot to hope for. But for me, I'm eager for a new experience in the universe. I've already been a human for three games, I want to make my own Quarian, Krogan, or Turian now, and roleplay someone from a very different perspective and background.
I suppose I could be entirely rational on the matter and admit that it doesn't make a big difference to be able to choose my race, but I'm not entirely rational, and for me it does make a big difference. I've never completed DA:O as anything but a City Elf. Something about that character archetype holds my interest in a way that the human characters don't (and the attatchment I have to that character has prevented me from playing a Dwarf. I do love dwarves though!
). And I firmly believe that whatever sacrifices were made to let me play a Qunari in DA:I were worth it, because of the joy I get from playing a Qunari, having horns, and having nobles scoff and call me an Oxman. DA:I would still be a fantastic game even if I could just play a Human, but for me it is greater for allowing me to be something else.
I also feel like it'll be a wasted opportunity if they choose not to include playable aliens in the campaign. This *is* something people have been asking for since the first game's release (probably even before that if I were to guess). This new Mass Effect game is basically a blank slate for the franchise, they could do almost anything they want with it. Why not include playable aliens now? (Aside from time, resource, or technical limitations which I understand) And if not now, when?