need to fix a bent strut

does this "need" to be done or will the boat be fine?

I don't notice anything on the water, but you can visibly see a slight bend in the strut, which in turn causes resistance on the prop shaft. My mechanic says you should be able to spin your prop with one finger while the boat is dry?? is this accurate?

Basically my concern is I can fix the bent strut for $1500 ish. Which is a lot of money to me. But I don't want to end up a year or 2 later paying 5k for a new tranny.

Like I said no visible symptoms on the water. no vibration, etc
thoughts?