What about the theory that the box turned people off the PS:T as much as anything? I for one fall into this category. I saw Black Isle and skulls and such but the box itself was so garish that I was turned off. But word of mouth got me to bite and I found my favorite CRPG of all time, complete with avatar and quote.
My point is that an attractive cover is probably alot more important than anyone would like to admit.
In addittion, if I'm not mistaken PS:T had a preview movie that came with IWD and BG2, but it didn't peak my interest either. It was too abstract.
2 cents
BTW love the boards!