WotC said that their surveys during 5e heavily leaned to wanting psionics using the existing spell casting mechanic. Not sure that meant they are spells in the polls / surveys - but people didn't want a new mechanic.
Aren't you conflating two things there?
People definitely said they didn't want Psionics using an entirely new mechanic, but I don't recall them also saying that people wanted Psionics to use the spell mechanics, just not something new like Psi die. I think I'd have remember if WotC claimed people wanted Psionic spells, because I'd have been incensed.
Personally I think there is room for both. I actually think it can work fine with spells if psions use the spell point system and there spells are class specifict - but that doesn't look like what we are getting. Not a big deal to me as we never use psionics.
I agree that there is, but my concern is that when you start making psionic spells, especially calling them things like "Tasha's Mind Whip" (not Mind Whip), you're very clearly establishing them as spells, and they can't really be re-used as psionics without creating a new, separate system, which WotC don't want to do.
Being able to manifest such effect by your will is blatantly supernatural (people can't do that in real life) and by most normal definitions would be magic. The definition of psionics in D&D has always been an incoherent mess. Psionics is just a pseudo-scientific sounding term for magic.
This is a lazy argument that has no substance to it. It's just about a semantic definition of magic (which itself is a bloody silly word). It's been knocking around since the 1980s. It doesn't matter if you call it "magic" or not. But Psionics is clearly not the SPELL-SLOT-BASED magic that all D&D casters use.