No character is truly "hard to play" if you've been playing them since release, and have the muscle memory at this point. I've been playing Kirby since 64, so I think he's easy as heck to play. I'm familiar with his mobility, frame data, range, etc. I think ZSS is really awkward to play, but if I'd been playing her since release, I wouldn't. I thought Falcon felt extremely weird at the beginning of smash 4 compared to brawl, but now I'm used to it. There are probably people who think Kirby is exceptionally easy to play, until they have to learn how to use ~55 B moves, and any ATs that might come with them, or how to use a command grab with a slow floaty character, or how drastically his combos and kill setups change depending on rage and his opponent's weight and gravity, or getting used to one of the few UpBs that doesn't ledgesnap and won't grab the ledge if you're facing the wrong way, or a DownB edgeguard that will kill you if you don't press B again, or press it too soon or too late, or mash it, etc. Then, like others have said, the difference between difficult to play and difficult to win with is a thing... but really smash is designed to be easier to play than traditional fighters at a basic level, and it is. And there's nothing wrong with that!
Also, it'd be neat if airdodges followed the same rules as ledgegrab invincibility; you get only one, until you hit the ground or get hit.