Even then, 300 was more of a fantasy than anything, more analogous to the Lord of the Rings push than the historical epic one.
Honestly, I think the problem was they tried to make predominantly mythological stories into historical pieces/ You've got Troy, which instead of portraying the real Trojan War, was just the Iliad without the Gods, and then you had King Arthur with a half-assed realistic intent. Alexander tried to make his mythos real instead of just portraying him as we think he was, Kingdom of Heaven was the only one that tried to be a conventional epic, and apparently is good in the director's intended version.
Great epics of the past, like Spartacus, Lawrence of Arabia, or Cleopatra deal with the story of what happened to them as it was known. Or Gladiator that has verisimilitude. Or popular ones like Clash of the Titans or the Steve Reeves Hercules films, that embraced the myths. Hell, I think that's what 300 did right, embracing the mythologizing of the battle that's happened in Herodotus, etc.
I think the folly in the new epics is trying to change, or create a new take on old stories while still retaining some of the original. You can't go on about Achilles and Hector without Apollo and Athena, and you can't go on about Arthur and Merlin without grails and Galahad and magic.
And Alexander is another category altogether, you can't just in general half-ass a movie about the most important person ever, and have him played by Colin Farrel to add insult to injury.
