Is it financially worthwile to use hollywood starts as VAs in games?

[Xen]

It's not a first.

Hayden Panettiere (who is gorgeous by the way), voiced Kairi in KH2 along with other celebs, whom I can't remember because I don't care for them.

I'd say it's worth it if the trend exists. If your budget allows you to hire these actors, then do.