You only want to get a guy with a specialty if you have a reason to do so. For example, I had a weird split with my games this season where I had lots of away games early and home games late. Add to that the fact that I got the #1 seed in my division (which means I play home playoff games) and it made a lot of sense for me to pick up a PR guy with Crowd Involvement to help my team out in home games. If you have older impact players, Career Extension can make sense but don't get one of those guys just for the hell of it.
mmh i don't buy every training a new doctor, and help on game shape is always usefull so i believe massage is always a usefull speciality.
When a slightly injured player come back to a game, it is better then not so this is always a usefull speciality.
During the time you own a PR, you always have home or away games so this bonus aren't bad ;)
Fitness is usefull as long, any player of your rooster have stamina higher then atrocious min, ok career extension could be sometimes without a sense ;)
So i would still say you can not compare then to a level of quality, and you don't have to pay a lot for the speciality(ok for the coaches it makes a difference).