I know that feel, bro. Mewtwo sucked in Melee. A lot of people wanted him cut and a lot of people were initially happy that he didn't come back in Bawl because he sucked.
Nowadays, people miss him. They realize what they had and wished they had it back. P:M probably helped, no doubt. I wish Mewtwo was back, and sure, I wish he was a bit better than he was in Melee (because come on, the most powerful Pokemon shouldn't be a pushover); however, even if Mewtwo came back and sucked yet again, I would still be so very happy, because he's my favorite Smash character. Just like yours is Jigglypuff. You would be crushed if Sakurai cut Jiggs. You hate it now when people say, "I wish Jigglypuff was gone," but you'd hate it even more when they'd say, "I'm glad Jigglypuff IS gone, she sucked anyway." That's how I felt when Mewtwo left.
I wouldn't wish that on anyone.
I'm glad Jiggs is back. I hope Mewtwo makes it, too, but we'll see. In the end, I hardly blame Jiggs. If anything, any beef I have is with Sakurai himself. He chose the roster two years ago. He made time to get everyone in he wanted to get in. Any character that was low priority or too difficult got left out again. If Sakurai feels like Mewtwo is low priority or too much work to do properly, then that's his decision to make. I think I'd be pissed off at him, but so long as he's in charge, that's just how it is. I'm just glad that, for you guys, Sakurai rates Jigglypuff pretty highly. That's something to be happy about.
I hope I have something to be equally as happy about very soon.