Honest opinion / thought dump:
Anyone expecting the first major customs-on tourney to radically alter the metagame has been setting themselves up for disappointment.
Unless there was some earth-shattering secret weapon hidden within these custom sets or a silent warrior waiting in the shadows to show us how it's done, EVO was never going to rock the metagame to its core. Top-tier characters are still top-tier because they have the toolkit and the wherewithal to deal with whatever comes their way; we know that no amount of custom shenanigans is going to suddenly made DK a hard counter to Sheik. That's just not realistic.
We've known in theory for a long time what customs can do: EVO is just testing whether our theories hold water or if we totally dropped the ball on it. We know more about customs and how they work in a major tourney than we did before EVO, which is good. We also know that customs, in addition to not being the game-breaking jankfest that had concerned folks beforehand, are not a magical panacea to suddenly make non-viable / semi-viable characters top-tier threats.
This is good. We've educated ourselves.
Yet it's still just a stepping stone. EVO was as much a testing ground for customs as it was an international tourney. We know now that some characters, in the right hands, can get further than they could in a customs-off environment. Villager especially reaped the rewards of this brave new world, though we saw some good stuff from other rarities as Bowser Jr, Mii Brawler, Palutena and DK. That's a good thing and a positive development towards a more robust, diverse meta.
It's not going to change things overnight, though. It's going to take time and effort from top players and a hell of a lot of community exposure to go places with the customs meta. The top-tiers were always going to dominate (with a few notable exceptions, which may or may not have been due to customs) because, well, they're top-tiers. A few new moves isn't going to suddenly rock the paradigm to its core. At best it just demonstrates that, yeah, things can be a tiny bit different, and there's room to improve.
That said, I think individual skill played as much a part as customs in creating a more dynamic roster. Correct me if I'm wrong, but aside from Wario's Fast Bike, did Abadango even use customs for any of his characters? How about Ally's Mario (I won't cite Marth as that was really an anomaly) or Dabuz's Olimar? If they did use customs, they definitely weren't the focus of their playstyle. I even would go so far as to say that individual skill made more of a difference in the highest levels of play than customs did.
Regardless, this isn't a treatise in defence of customs. Takeaway of this is that I think it's heedlessly optimistic to think this was going to be the fall of Sheik and the rise of DK (to use an arbitrary yet relevant example). What it is, is a glimpse into a potential evolution of the meta that is yet to come, though not for a very long time indeed.
That's why I think EVO is important, and why I think that, for all its success and excitement, we have a very long way to go.
Apologies if none of this made any sense, I'm just tossing out thoughts as they come to me. There's a kernel of rationality in there if you can find it, god rest your errant soul.
, 2 
