Most DMs who don't want to learn a new completely new system will ban it. I think that's a primary reason why Psionics gets banned.
I think designers want their new things to be used by many groups, so I feel that Psionics should be "friendly" to casually invested DMs.
On the one hand... yes. Designers want people to use our stuff.
On the other hand, you can make something that isn't "Spellcasting, but call it Psionics" and have it be friendly to casually invested DMs.
And, let's be honest, if WotC wanted the "Psionics are just Spells" character class they'd just release that with a new spell list. Nothing is stopping them from doing that and no matter what they release tons of people are going to buy it and use it in their games.
The issue is: The designers don't want to make that. Which is why Mearls spent months pounding his head against the Mystic while working for WotC, and eventually started in on the Psyker now that he's an independent.
And funnily enough, he's kinda taking the same path I did (upgradeable Cantrips as Powers).
Definitely talking about previous editions. Especially 2e psionics. If a DM has to learn about the 5 psionic attack and defense modes because of just one player or MTHAC0, that's already grounds for banning.
Much as I love the Psionics Handbook and it was my introduction into the idea of Psionics as a game mechanic... Yeah. It was freaking horrendous.
3e did it "Better" but just went all in on it being "Basically just Magic". And then 4e did a great job of the classes but since everything was heavily templated it felt "Samey", overall, to other classes... Just with a different flair.
But yeah. It's all about finding an elegant way to make it different. And such ways do exist. WotC just hasn't found them, yet.