Fairly sound actually. Look, evolution is not a magical force, nor is it omniscient. All evolution is a differential of death rate. Driven by:
a) Maladaptations resulting in early death. Particularly death prior to sexual maturity.
b) Maladaptations resulting in reduced fertility/reproductive performance/mate attraction.
And that, by and large, is it for ‘fast evolution’ - the other, even slower kind, is the micro-tweaking involved in shaping and perfecting facets of our organs and general performance - these having lesser overall impact on fitness, at least in a relatively stable enviroment.
But with excess human populations every ugly slacker dumbass can reproduce with someone, those with errectile problems can viagra their troubles away, infertile couples have any number of therapies available. Diseases don’t stay deadly for long enough, technology reduces the wear and tear on our bodies resulting in longer lifespans. etc. etc. etc. Evolution’s sole method of quality control, death, has had most of its claws pulled.
Evolution, of the genetic driven type, has all but stopped. We are what we are, and have been pretty much so for millenia. Don’t expect genetic drift to save us. We’ll all be dead by then.
Our conscious minds effect only cultural change, not evolution in a strict sense.
Chance, and changes in enviromental circumstance. Right place, right time, no other pressing engagements.
No reason at all.
Need…? Need…? There’s no ‘need’ involved. It just did, because at that point its platform - our brains - had complexified enough to support it. Need, reason, purpose - forget them with relation to evolution and nature they are purely subjective bullshit human constructs.
I’m not anything - what is a ‘philosopher’ anyway…? And it seems regurgitating old wine is necessary sometimes, to keep people’s flights of fancy in check.
Pragmatism. Inevitabilism. We all adopt perspectives. Nothing is new under the sun.
Look, the real question is “Why am I trying to burst your bubble…?” And the answer is because I like you. You’ve lived a very interesting life and stuck by your principles throughout it. And I hate to see you waste your time in the realm of ‘should’ and ‘ought’ and ‘it would be better’.
I mean, sans bells and whistles, this thread is basically based on the observation that “people should grow the fuck up” - And you are berating me for being hackneyed…? 
I mean Jesus.
The vast majority of people will not grow up until some imperative drives them. That imperative will have to be provided externally by society as a whole, incrementally - like electric/petrol hybrids - rather than all at once. Eco-economy will slowly make advances and public/politic opinion slowly come round as incentives are gradually introduced to make them change their minds. There will be early adopters, band-wagon jumpers, and then the crowd joining en-masse, as with any new fashion. Some facets of eco-economy will only become viable after a certain threshold of mass-acceptance has been crossed - just like mobile phone networks and fax machines.
But it has its own speed, and it is frankly a toss up as to whether it will come in time to save the planet from major disaster.
Now stop telling people to grow up, and start lobbying the internet masses about that cheap bio-fuel doo-dah you have in your back garden, because that’s a tactic that may bear fruit, and not just piss people off.