I've got no objection at all to discussing preferences for different versions of background lore. But I don't agree that the lore in the PDF fundamentally changes the nature of the class - because (i) it is fairly continuous with the 4e lore, and (ii) it is easily ignored with no effect at all on the mechanics or the flavour they generate.
Upthread @
MoonSong(Kaiilurker) asserted that "From Magic-user to Wizard:Mage there is little difference, the mechanics remain pretty much the same between editions, the flavor remains unchanged as are the aesthetics, only the name changed." But in fact, as Hussar points out, the flavour has changed radically. In AD&D (at least 1st ed) spells were
memorised, and casting them involved channelling power from the positive and negative material planes. Since 3E spells are
prepared, not memorised, and there is nothing about channelling power from the positive or negative material planes. In 5e, all spells involve manipulating "the weave", which hitherto was a purely FR notion.
In the same way that many players just ignore these shifting background flavours for magic-use, so I'm sure they can and will ignore shifting background flavours for psionics. Ultimately I think it's just not that big a deal.