So, the Reapers return and attack Earth. Who would have guessed, eh? So, Shepard has to go and unite the galaxy against the Reapers - again. Who would've guessed, eh? With so much at stake and time being of essence, I'm betting Shepard still has ample time to go rescuing puppies and solving petty crimes for some random NPC while the Earth is under attack by the most ultimate badasses of the universe (gotta have sidequests). He also has ample time to prove himself to his teammates by helping them to solve their father issues or perhaps aid them in getting a divorce. The same teammates, BTW, who've been fighting with him against the Reapers (etc.) since game 1. So, for the Nth time we're helping them, before they'll help us fully, before they'll give use of their special talent/story point (one use in one part of the endgame) to the team - IOW, we're doing the loyalty quests for them, again.
I bet Shepard also has ample time to have the Normandy act as a mining ship while he gathers minerals to improve the ship (one screenshot shows mineral tallies) - this could not be done by any other ship (I dunno, like a mining ship perhaps), nor the improvements done like-the-hell-now-pay-the-bill-later because Earth is being destroyed and the fate of the entire Human race is at stake; nope, Shepard has to go, pay the bill/get the minerals on his own and use a warship for this.
While all this is going on, Shepard (being the guy/gal that he/she is) has also ample time to go banging humans and aliens of any gender all around the galaxy and use his/her special form of persuasion by collar-grabbing people left and right. If he/she has some extra time on his/her hands, the good Commander can go endorsing all the shops in the Citadel to get a small discount in them. Universe saving isn't a big enough cause, you see.
Also, for some reason the Cerberus opposes Shepard and by doing so helps the Reapers, who are (need I remind you) out to eliminate all sentient life - but I guess Cerberus doesn't count themselves sentient. I sure don't. Why don't they just shoot themselves in the head. It's quicker and the end result is the same.
And so on and so forth. Mass Effect series ceased to make any sense to me long time ago. ME1 was OK and had promise of a good series, ME2 moved to the wrong direction RPG-wise, plus the story went down the drain. I'm seeing the same pattern as with the Dragon Age series here. The first game is OK and holds promise, then the second one goes "retardo" and trashes any hope given by the first. As to the third, it remains to be seen (in both cases). I might still buy ME3, to complete the series, but I don't have much hope of it being a good RPG or even a good shooter/RPG (firefights looked the same as in ME2, cover-crouching whack-a-mole, ahoy!). Too bad, a good AAA sci-fi CRPG would've been just what the doctor ordered (no pun intended, Bio).
