This would be handy.
I have seen tests that actually show that lowering the signal strength in situations where there are a lot of signals, can in some cases give better reception since it does not have to fight with other networks.
I noticed that changing country will change not only the frequencies available, but also the strength. For some reason if I leave it on the default USA, I have 5 bars on my 5GHz network when i'm in a certain spot in my apartment, but if I change the router to Sweden I only get 3 bars. I'm not sure if this is due to signal strength or frequencies, also i did not test further if it effected throughput, having to restart the router every time I change made it to much of an effort to do any in-depth testing. I noticed it one of the times I set up the router from factory default.