The only real reason to do savage is for the thrill of beating it - it’s a nice feeling after all that work learning the phases to finally kill it.

The only reason to do it for the gear is if you intend to do Ultimate after.

There’s nothing else in the game outside of ultimate that requires savage gear and your power gain gets “reset” when the next tier comes out, which along with it, comes new crafted gear which is better than the gear you earned from the previous savage tier.