Well they were the last one's released...
So yeah. Customs is an interesting thing, they seem cemented in the game as they are, and a sort of forgotten pipe dream. Good idea that just flat out perished.
There's still updates coming - and I'd love to see the more fleshed out ones come into play much later into the development of the meta (Ice balls, Falco/Fox/Wolf blaster, Mii gunner options, distant thunder, Kirby's Brawl hammer, ice breath, bomb variations, ZSS blasters, Ganon sword, fire arrow, variations of counter, Ness customs, melee boomerang, variations of firebird/fox and phantasm save for twisting fox, etc.)