arguably, the old system always made you take armor or HP yellows, AP or MR blues, or MPen or AD reds. the only real "diversity" they had was what quints you decided to take, which more often then not, were more offensive.
ad champs almost always took AD reds, armor yellows, mixed blues.
ap champs took AP quints and blues, HP yellows, and mixed reds (mostly MPen)
granted some people took scaling runes, it didn't really allow for any versatility unlike this system. lets take annie for example. you can either go:
electrocute for full burst
predator to catch people out
aery or comet for earlygame poke.
the old rune system would have left you with only full burst
not agreeing or refuting the post you made, I just disagree that the old system added more diversity.