Mo hit on the best reason I can think of...accuracy. not all .270's like 130's. I shoot 130BT handloads and 150 speer hot-cor handloads. The rifle is set for the 130's that shoot sub-inch and the 150's shoot minute-of-deer in the woods. I see the 150's as an insurance policy up close and the fact I just like working up new loads...
Shoot whatever your rifle likes.