That's a big change (the elder's age requirement change). It was always the case that 30 was (unofficially) the minimum age to be appointed - I remember several well qualified JWs who patiently had to wait till their 30th birthday before being made up as an elder.
Although never officially stated , I think Timothy was often cited as he was in his 30's when recommended by Paul and of course Jesus who was baptised when 30. Very occasionally a slightly younger guy was made an elder but that was very much the exception. My cousin was appointed when he was 28 and even that was really unusual even though he was a pioneer / Kingdom Construction worker & very zealous JW.
Appointing elders in their "early 20's" does seem a sign of desperation for people to take responsibility in the congregation and is somewhat stretching the definition of an "older man"!