With the rise of the city, kleos was replaced for the most part by arete as a driving goal for the citizen who wanted to make a name for themselves. Arete is "excellence" and you can show that in many fields, not just combat. Kleos undermines the cohesion and community of the phalanx, which is a collective endeavour of all the important citizens.

It wasn't just the Greeks who changed their opinion of personal glory - the Romans had a similar shift when they adopted the phalanx. The prescribed punishment for leaving the phalanx to seek individual combat was as harsh as that if you fled.

That's not to say people didn't read Homer and dream of glory through conquest - Alexander the "Great" was channelling his inner Achilles most of the time, and before he thought he was a god, he thought he was a hero from the epics.