The problem with Aegon is that people are drinking Vary's Kool Aid instead of looking at him with their own eyes. Yes, his education was supposed to make him humble and understanding of the plight of the common man etc., but it clearly didn't work. He freaks out over a game, speaks derisively over baby that was killed so he could live and expects Daenerys to fall over for him. He also accepts Tyrion's advice uncritically while Tyrion's wasn't even particularly serious about him. Oh, and he needed to be saved by Tyrion when attacked (all that fencing lessons sure paid off).
What's funny is that all the things you bring in favor of him can seen from a totally opposite perspective. Rewarding Rolly Duckfield? Lack of political sense, that Kingsguard place could win him support of some lord if he didn't waste it on a nobody. Brave enough to lead an attack himself? More like foolish, overconfident and reckless.