If it's sore stretching with the longer stem then so be it. One gets used to it and after a while the body adjusts.
		
		
	 
I have known so many people who will spend several hours riding their bike , on big rides, and go out for shorter rides in between, or commute, but wont spend a few minutes each day doing some really simple stretching exercises. 
Tbh you don't evn need to do them every day once you get flexible. Sitting up straight and some simple core exercises ,here and there, aren't exactly hard work either.
 It doesn't take long to lose flexibility, as the years pile on, so the stem gets shorter and the bars higher and then they moan how much harder it is to cycle into a headwind . 
There are cyclists who don't have the choice, because the back is ruined from things like accidents and arthritis, but the majority have become chair shaped ,and as tight as a drum , at quite an early age which will lead to non-cycling related problems, later in life.