An RA is NOT a common occurence, and the QRH in case of engine failures or issues correctly focusses first on SECURING the Aircraft and systems.
Neither is an engine failure, but I think we shall agree to disagreed on the issue. I thought securing the a/c involved all aspects of safety and avoiding an RA which you can not comply with IMHO fits neatly into that category. The 2 seconds it takes to move one switch 1 click to avoid a whole plethora of panic in an unpredictable future seems, for a professional operator, a minute distraction. Securing the engine is not a rushed action. PF is doing the A.N. bit and PM can twiddle a little knob.
There was an occurrence at hight FL. at night, where the crew had an engine failure. They forgot the basic A.N.C. and went straight for Engine Failure procedure. Good old simulator check ride stuff. After a very very short time, while they will still trying to figure out exactly what was happening, they got the stick shaker warning. They are now in RVSM with a SE stall recovery manoeuvre. Imagine if they then received an RA restricting their descent. Who here would ignore it or try, in vain, to comply. One little knob twiddled one little click would avoid that.
I do not have stats, but I suspect there are more RA's worldwide than engine failures. All I want to do is ensure the best chance of a safe outcome.