Apart from team training in FT, maybe when training JS or IS could add something in FT for the players that are trained only.
I had a C with great FT once (I think 15 or 16). His IS was 2 skills lower than my PF's. But many times my C took more shots because if fouled, he had greater chance to score. So great (not good, but great) FT skill could make a player to shoot more despite being surrounder by better shooters.
No, FT is important, but not as important as other skills in terms of productivity and value.