Okay. I can totally see your point in the matter. You want a tang because every great tank has one, they are beautiful, etc etc etc etc.
Here are the negatives. Having a blue tang in a 75 gallon tank is a bad idea because that tank is small and it will stress out the fish. This will lead to ich and ich will infect every fish in your tank. If not treated properly, it will kill everything and you will wish that you never got the fish. Even if you return the fish right when you see the ich it will already be in the system and your other fish will get it.
I wanted a tang for my tank but decide against it due to this reason. Trust me, there are many many other big fish that will do GREAT in that tank. Even other types of tangs like a kole or bristletooth, but blue tangs are KNOWN for getting ich when introduced into the tank.
Goodluck with everything. If you decide to get the tang i have a feeling that i should explain to you how to treat and help prevent ich.