You say you don't want Mewtwo's power to be buffed, and yet all you do is complain how he can't easily get KOs at like 70% like some heavyweights can?
The problem with focusing only on Mewtwo's kill percents is that you neglect everything else Mewtwo has: good mobility, the strongest projectile in the game with a reflector on top and fantastic recovery and edgeguarding. His throws inflict high damage and so do his aerials. He could arguably be a rather functional character without any combos but he has them anyway, and are generally far longer than any heavy could ever manage, and he has more than just dtilt to start them; jab, utilt, nair and even short-hopped uairs on tall opponents all can be very effective combo starters with practice. Dtilt is just his safest and most versatile.
The community is doing more than just curling up in defeat and crying for buffs. The existence of these threads should be enough to prove that:
http://smashboards.com/threads/mewtwos-big-book-o-combos-8-characters-done.413911/
http://smashboards.com/threads/the-psychic-log-mewtwos-metagame-discussion.415950/
Or are these threads and the people working on them sabotaging Mewtwo's chances as well by trying to find what makes Mewtwo work? Because the buff-listing thread is SO productive.
You have every right to believe Mewtwo is still too frail to justify all of these positive traits, but as it is glass cannon (of the defensive nature, mind you) is really the best way to describe him for those who don't see him as trash.