On top of the other reasons mentioned (can create almost any item due to MiC/Erudites), Psionic Artificers are also not subject to the same restrictions as regular ones. Namely, a regular Artificer's scrolls and wands are neither divine nor arcane, making them difficult for other classes to use; but psionic artificer items are still psionic, so psions, wilders etc. can use them just fine.

The MiC rules make them capable of tricks that no other manifester can match as well, such as emulating Psionic Genesis to create a scroll of Regular Genesis.