Thanks for reminding me of that. It's something I wish they had developed and I've thought about a lot. The real reason, was most likely, as Maria has already said, "the writers forgot", but your explanations are interesting. I think that they also wanted to make the Founders very unusual, and telekinetic Vorta would have taken something away from that. They developed the Jem' Hadar quite well, but we only ever seemed to see the same Vorta, Weyoun. Maybe it was only the Weyouns who were non-telekinetic Vorta? Maybe different Vortas have different abilities?