Why would they do that?
To get people to buy the book?
One thing to keep in mind about v3.0e psionics, is MAD casting.
As in Wisdom for Clairsentience, Dex for Psychoportation, Cha for Telepathy, etc ...
But v3.5e got rid of that, and made Wis the "casting" stat for PsyWars.
The consolidation makes PsyWar an easier class to build, and Psions a whole lot better.
I think the easy CO concensus, is that 3.5 psi is a better system than 3.0, but it isn't walk-off easy to learn it.
It looks the same, it feels almost the same, but lots of little differences are in there.
The old Psi-board on wizards.com still has some of the info threads.
Some of the old psi- gang, has moved on to dreamscarred press. (gawain's link just above)
" ... Nerfed ... "
hmm ... it's possible that with an all-in 3.0 build and total CO-tricks, that a 3.0 PsyWar
might do some things
different or slightly better, than a 3.5 PsyWar. There is so much more material now official and otherwise, for 3.5
I'd have to say no, that a 3.5 psywar would be stronger, but maybe not noticeably stronger til later levels.