Buying lower-powered motors

[plenty]

Newcomer here. I feel like this is a silly question but have asked around and searched and not found an answer yet...

Say I'm looking to buy a motor. I race in situations where I can use the power of a 7.5t (or at least it's fun to have it), but also others where less power is preferable (tight tracks, low grip).

What's the benefit of buying a 7.5t plus say a 10.5t versus simply using the 7.5t and adjusting throttle EPA and expo via the radio, and esc settings? Which is what I've been doing so far.