The only reason I see for people to whine about customs is because they don't want to learn how to deal with them (hey, I didn't say it was a good reason).
Honestly, they should all just be allowed. I started trying the Mii Brawler myself a while ago, and I actually liked playing as the Brawler. It's quite unfortunate that I just never get a chance to try him due to ruleset restrictions all over the place with their moves. I've barely gotten to play him and rarely get any chances to practice him. The only thing I get is the weight and height to be kept default, but come on, that should be the only restriction if there has to be one (and even then).
Yesterday night, I went to Neo Canadia 5, the Toronto monthly. In Losers Round 6, I faced off against IceNinja, a very good Palutena player. We had a very close set in the end (I won 2-1, last stock both at high %), but honestly, it was due to him getting greedy with F-smash, so I went in for a punish.
Can you imagine if he would've had celestial fireworks to properly hit me from mid-range? What about Lightweight, to keep up with Fox's jittery movement? Honestly, he would've won, and he was also doing the sickest things by ledge-cancelling Warp using Battlefield's platforms. I kinda felt bad that I beat him, because that wasn't the character he loves to play and dedicates so much time into, it was just a shell of a character that could be much better.
Back to Mii: I tried playing Brawler last night at Neo Canadia in Losers Round 7 after I got destroyed vs Ryoko on game 1. He's a very solid ZSS player, and that matchup is just hard as hell for Fox. I switched to Mii, did much better with it, but in the end I lost. How much do I wish I could've used Helicopter Kick to seal KO's. It sucks that I couldn't use Feint Jump either to avoid the paralyzer shots and essentially make it back onstage.
And to further support Customs, not just for Palu and Miis, but for everyone: I want to be able to use Flying Fox (faster recovery), Big Reflector (for the windbox), and get rid of my incredibly crappy rapid fire Blaster that just plain sucks in this game and its only use is to force approaches from opponents standing too far to punish me. I may not have a right to complain when Fox is a good character in the non-Custom meta, but it infuriates me every time I'm forced offstage and knowing that Up-B puts a big "Hit me please" sign on my forehead.
This thread might have gotten derailed, but you know what? The point it's getting across right now is what the meta should be: turn Customs On. What worries me the most is EVO doing Smash4 after the Apex ruleset, which I sincerely hope it doesn't happen.