The idea behind customs is great, but moves like DK's upB and Villager's camp seed are very good counter arguments. It's why I have slowly shifted back to non custom play. I can see the problem.
There was a recent video on this. The recent patch should have killed Villager's custom camping strategy pretty good too, which was never truly viable enough to win a tournament anyway.
That said, I sympathize with some of the customs jank, and certainly wouldn't want ESAM to kill me the way he's been killing some people in tournaments lately. I agree with the assertion that part of the reason we went to customs was because it seemed like Diddy was so in control of the meta that the community was desperate to find something else. Diddy play was no fun to watch, a Diddy ditto was just two players hiding in their shield waiting for one Diddy to throw his banana first.
But admitting that, I don't want to see customs go away. As a Bowser main I just can't give up dash slash without a fight. DK, Ganondorf, Bowser, Charizard, Lucina, Palutena, Mii characters and others all gain from customs without becoming crazy high tier. Recent customs tier lists don't put any of these characters in high tier, IIRC. But customs give these characters (and some I surely missed) a chance where they had none. Other characters gain options depending on playstyle (Mega Man, Dedede, Falco, Fox (ok maybe a bit more than that), Diddy, Lucario, Samus and others. To take all these things away really sucks. I'd much rather ban exploitable customs than see them go away, and I say this while playing a character that loses many customs matchups. What happens at EVO may well lead to some of those future bans, we'll see. ESAM is probably going to force the issue.
I understand the negatives of customs. I think the benefits outweigh them, barring a few exceptions. I totally get that customs can create lazy play, but it's up to the opponent to punish that lazy play and force the lazy player to work. Given time, this will happen.
There are at least a couple more patches coming for Smash 4. A reasonable nerf (ie not what they did to Diddy this month) to Sheik and Rosalina (maybe Luigi/Pikachu also), some more low tier buffs, a couple exploitable customs banned and we're looking at a pretty balanced game. It takes practice to avoid or learn how to deal with certain moves? Big deal, it takes way more practice to wave dash and L cancel, and I don't see Melee players bitching. The Smash 4 scene has plenty of time to figure stuff out.