It's very short-sighted to say that the future doesn't matter when it
did matter and does matter. Why did Garrus, Wrex, Tali, etc. help you in
the first place? Because they saw the danger of the Reapers. They
didn't up and decide to help Shepard because he/she was such an awesome
person that they wanted to hang out with him/her. Those friendships
develop naturally during the course of Shepard's fight to stop the
Reapers, but those people initially stay with Shepard because they want
to make really sure that there's a future for themselves and their
people.
I certainly didn't fight against Sovereign or the
Collectors because I loved Kaidan or because I developed a deep and
abiding friendship with Garrus. I was fighting for something bigger than
any of that. My friends and LIs inspired loyalty and feelings of
camaraderie and were an important part of the journey. They gave me a
reason to keep going in what seemed like a futile fight to be sure, but
it was ultimately about finding a way to break the cycle and to make
certain that there would be a future for others - even if that didn't
include my Shepard or my friends.
If you're a determined
pessimist, then of course you believe that there's no future or hope and
that everything you love is gone, in which case so be it. Some of us
just don't see it that way and have an optimistic outlook as far as that
goes.
''Determined pessimist''? The hell does that mean? Let's examine the facts a little bit...
1. In 2 of 3 endings, the Citadel blows up. By every single law of physics in existence, this means Earth is doomed, because the explosion and then crash of an object of 7.11 billion tons of mass will absolutely devastate Earth. Not to mention the tons of debris from the space battle. Or the Reaper carcasses in Destroy. The planet supposed to now house all those stranded races. Is doomed. Happy future much?
2. No race save maybe the Geth and very very maybe Quarians will ever see home again. The problems of conventionnal space travel, including food, fuel and the need to discharge drive cores, make such a voyage impossible. They are stranded. On a doomed planet. Happy future?
3. Outlying colonies are doomed. Many are not self-sufficient, and/or have ships that can get them elsewhere and/or the capability to build more. This also includes death world such as Tuchanka. Which we spent a good deal of the game saving. To see it doomed regardless. Happy future?
4. As far as we know, the damn Yaghs are the next in line for spaceflight. They are even worse than the Krogans.
5. I don't care what Stargazer implies, the crew (whose survival is, according to the codex and basic physics again, is impossible, but I digress) is also doomed. Tali and Garrus will starve. There are, what, 20 other people on the ship? Nowhere near enough to sustain a population. That's not even getting in the implication of Cortez and Traynor being possibly forced to, erm, participate in the effort

.
6. The galaxy cannot develop an equivalent to the Mass Relays. The knowledge and ressources required are simply beyond our means (before you pull the Crucible in this, we had the plans and a galaxy's worth of ressources to build it). We are stuck in short-range, risky space travel. Until Helium-3 and/or eezo runs out in proximity. And, yet again, logically Earth is dust in 2 endings out of 3.
At this point, it's more like the pro-enders are hopelessly determined optimists when they say the future is bright. Refute every single point I made and then we can debate. Until then, I have not seen one good argument from you guys.