If this were actually true then evolution would go ahead and make everyone absolutely cowardly. Evolution works because traits that are helpful to an individual become more common; because the individuals with those traits reproduce more. Nothing stops evolution going down paths that are bad for the species.
(Of course, if it gets so bad that the species goes extinct then we simply won't see that species any more. But nothing prevents this from happening.)
It isn't actually true though: risks have their rewards.
Individuals don't evolve at all. Evolution is changes in gene frequency over time.
What I think you're trying to talk about is macroevolution, where species that happen to have certain traits survive longer than other species. Sure, this sort of thing happens. But I was responding to the claim that "absolute cowardice [is] beneficial to an individual" and noting what would happen to the level of cowardice in a population if that were actually true.
It is absolutely not beneficial to the individual to put energy out to try to have sex, put energy into offspring, or to take risks for others. However all of those behaviors have tended to be beneficial for the genes that the individual has because the others who are helped are likely to have the genes producing that behavior. Therefore all of those behaviors have evolved notwithstanding the fact that they are inconvenient for individuals with those genes.
The existence of traits like courage is far better explained by sexual selection. Women throughout history have always strongly preferred courageous men to cowardly ones. This is only partially cancelled out by the fact that courageous men tend to die more often.
As civilization continues to advance, and fewer and fewer people die before childbearing age, I'd expect the balance between sexual selection and survival selection to tip even more strongly in favour of sexual selection, so it's quite likely that (even absent widespread genetic modification) the people of the future will indeed tend to be "sexier" than the people of the present.
(Partially cancelling this out is the idiocracy effect whereby poor dumb folks have more children; I can't estimate which is more powerful.)
That's not an explanation. Why do women prefer courageous men?
Do you mean to imply that courage is like a Peacock's tail? It doesn't help a man survive, but it signals that he must be really good at surviving in other ways.
It depends on what you mean by helpful. If you mean helpful in helping them live longer, then it is patently false. Look at peacocks feathers as one famous example.
In any species which require two to reproduce, you also have to be able to attract a mate (generally mostly on the male side), and that may require bravery, willingness to make expensive displays of power, and all kinds of other things that may go against the best way for the individual to survive.
Similarly, in a species that produces few off spring, those members also need to help ensure the off spring survive. This may involve charging into fights you could have run from so your off spring can run, searching for far more food then you need for yourself possibly at great risk, etc. In short again other traits that may go against the individuals personal survival.
(edit: spelling)
Evolution is a game of balance. On the face of it, a predator being faster and stronger so that it can catch more prey seems like an obvious benefit that would catch on. But the time, energy and resources to do that might draw from what's needed to reproduce and raise young.
Dumbly repeating procedures that are known to work without analysis will not only cause stagnation, but also likely cause industrial and environmental collapse unless a system is so tightly controlled that it is impossible for any procedure to lose effectiveness. And unless technological improvement is impossible, this is clearly a suboptimal survival strategy, as survivability may not be improved.