If that was merely the intent, then there is no need for the substitution level to eliminate Wild Talent.
There's no "need" for it, no. I don't know what the actual mechanics of the substitute level are, but it probably adds a little power and/or flavor for specifically-kalashtar soulknives. The purpose of the sub level isn't to remove Wild Talent ... instead the sub level removes an extraneous ability in favor of something else.
yet despite this, people insist that fists are not natural weapons.
In 3.0, you mean? Technically, depending on other definitions and errata/FAQ, they may be right. Which is why that text was specifically added in 3.5, so that what the rules say matches what was intended.
Look, you were talking about the kalashtar sub level. Assume a kalashtar PC takes the sub level. Now ... where in
that character's rules-set does it say that a PP reserve is needed to manifest a mind blade?
It doesn't. Because it isn't. In 3.0, a PP reserve was needed. In 3.5, it isn't, probably because -- as someone pointed out -- it is an absolutely
trivial matter to drain 1 or 2 PP from an otherwise non-psionic soulknife and
completely remove his entire class function. I'd be very surprised if it would take more than a second-level spell or power to do so.
Being able to strip a character's entire concept and combat ability by means of a second-level spell is bad game design. When they realized that, between 3.0 and 3.5, they fixed it, and simply forgot to remove an extraneous phrase when they did it.