I think you mistake recognizing what self-sacrifice is; and seeing how a person could, as a proud "Marine", think of the greater good for ignorance or stupidity. One of the Marine codes, I believe, is selflessness. Few stories have opportunity to truly portray that. This one did. Now, you can take that Neaderthal statement and, possibly, rethink it in that light.
I go eat DNA a day now. DNA good! 
No, but you have apparently not understood much of the critique of the ending:
A: Catalyst logic and plot problems.
It's a bad ending, because the logic of the catalyst doesn't make sense if you have a rudimentary understanding of...well that the universe is big.
B: Lack of consequences from earlier games.
Personally I think it was hard to incorporate all of it... and war assets was pretty much the best they could do, but there could have been more acknowledgement of what happened in earlier games. Krogan cure fail ...Not having to go to rannoch at all.
C: The various war assets not shown off, making the gathering feel superflous.
If the war assets was the best they could do, they really should have made more of an effort, to show em off badassedly.
D: Not emotionally engaging enough.
Yes, we all knew shep was a soldier and sacrifice is so completely expected... That it's no surprise. We've seen it a 100 times before and if it needs to be there, it should have been done in such a way that it left us in tears. Genuine quality!
Or, as I've said it everytime I've critiqued the ending, put the squadmates and npc's that people felt just as attached to, or even more so, in peril. They should have sacrificed those or have shepard sacrifice her/himself to save those... rather than faceless trillions.
E: Not emotionally diverse enough.
The endings are emotionally grey, grey, grey... As I've said many times in my critique. A good dark ending needs to leave you in tears, a grey ending needs to leave you in tears and happy at the same time. A happy ending needs to leave you happy... For maximum impact and variety, have all 3. This is one of the points where shepard and squaddies surviving comes in. As reward for doing everything right on maximum difficulty or something. As a necessary contrast...
F: Lack of choice in the endings.
Can't be a douchebag and sacrifice the world, squadmates or just the squadmates you don't like to survive. Can't be good at fighting, diplomacy and strategy and survive. You have to allmost deliberately sabotage yourself to make it so the characters you care about die... Which is where, it feels like the real sacrifice is...
... The problem ain't selfsacrifice... it's a question of quality...
And we know that bioware can write emotionally impacting stories. Mordins sacrifice and tali dying.
EDIT and PS: I don't think the mass effect series and me3 sucks... I like them alot and I highly recommend them to people. I just think the ending wasn't up to standard and the series deserved a better ending.