Religious fanatics would grow tails, solely for the purpose of being ashamed of them and tucking them away in the trousers. Tyrannical regimes would gleefully lop off their subjects tails for minor transgressions. The possibilities are vast. The sure sign of a mature technology is its adoption by the pornography industry - we saw it with the VCR, the telephone and the internet. I think the genetically engineered tail would be taken up pretty quickly.
Pornography provides the impetus, then 'mature industry' picks it up.
Inbreeding also caused some characters in Gabriel Garcia Marquez's One Hundred Years Of Solitude to have small tails. I want a tail like Lucy's. The possibilities for dating boggle the mind. Perhaps having a prehensile tail is something that runs counter to developing intelligence. Perhaps tails would actually help us to develop intelligence.