That's the reason I always hear as to why some 
other cels were never released -- namely, 
Evangelion(spelling optional) cels.

Personally, I would think it would be in the best 
interests of all the copyright holders to get 
their butts in line and decide a way to divvy up 
the profits from selling the cels. . . But that's 
just me.

Many Sharp Smiles,
--Drac