Aside from a tighter cover system, better graphics and interesting characters, ME2 was the worst ME game to me.
Between planet scanning and the way dumbed down skill tree... 
Anyway, I'd much rather be on foot exploring a planet for my resources and upgrades, vs play a boring mini game where I have to repetitive rotate and probe a sphere to progress properly. My immersion suffered a critical mission failure in ME2.
That's...nice? Kind of irrelevant to what I was saying. The point is that something that is, ostensibly, totally optional, is often not really viewed by the player base as totally optional. If that thing is pure drudgery - again,
as perceived by the playerbase - then it's a Bad Thing.
For instance, you think that it is much more
immersive for a space Special Forces operative and CO of a spaceship, in the future, to be personally going out on foot to planets to "gather resources" rather than sending out drones to do the gathering for her. This is, on even the slightest critical examination, ridiculous. (That the gathering is even necessary or possible at all is pretty silly too.) This is a complaint that is not wrong, because you're the one who determines what is 'immersive' for you, but it is based on idiosyncratic beliefs, so it is easy to ignore. But a similar complaint - that resource-gathering in ME2 was a boring time-sink - is
not easy to ignore, because planet scanning was, by any reasonable definition, very boring, and even though it was not
totally and fully necessary to beat the game it still had a sizable impact on gameplay and as such was viewed by many people as something that Could Not Be Avoided.
So, to bring this full circle, you claiming that upgrading weapons via drops would not be totally and fully necessary is irrelevant. That would not stop the complaints, because upgrading weapons is a thing that makes life easier for players in games and forcing people to slog through the old ME1 cumbersome inventory nightmare for them would be a Problem for them.
I would imagine someone on his team would make up for his lack of an AR with their own. 
So you think, like, American Green Berets regularly go out on ops where
some of the dudes are just packing Berettas and have to scavenge AKs from the people that they kill?
Come on. N7 graduates are Special Forces. They get the best stuff for what they do
before they go into combat, unless combat is a surprise.