"Why do we only have two Kalos mega evolutions?" because mega evolutions were initially intended to bring new life into older Pokemon, which also explains why Gen 5 did not get that many megas at the time
Ash not getting a Lucario until the very last season of the main Pokemon anime series felt very off to me Ever since the Lucario movie and it being confirmed that he can read auras, I'd always imagined him getting one way sooner