He burned thousands of Reachmen for daring to meet him in battle. He carved out a huge lump of Westeros and called it the Crownlands. He brought every kingdom to heal and made its leaders into his servants.
And on top of that, Aegon never had those lords betray him and side with a man who would have murdered his line and raped his wife/sister and mother. Aegon would never have been forgiving to men whk supported a house that caused numerous rebelliins and threatened to destroy his line. Cruelty is subjective.
Yeah, he probably ensured that - but he didn't dethrone everyone and was still merciful in eyes of those, he defeated and who yielded. He took no lands from Stark, took nothing from the Westerlands and also accepted the Arryns willingly surrendering.
That's the difference. He wasn't protective around territory and claimed any single piece from any loseing faction for himself while not extinquishing entire families.
Plus the people he killed with Dragons were fighting against him mid-war - of course they would get burned, but by their own risk. If you have a weapon and run willingly into a flying Chainsaw, which can also shoot lasers - sure, go on.
Far by my knowledge he did however not summon men to the capital to let them all die there or burn them unarmed. That's the main thing why people weren't confident with lore-Aerys, as he simply overstepped borders, while violateing in the same way the guest right in eyes of others.
Either way, it's not an honorable death to get burnt alive, while being unarmed. Medieval people get uneasy about this more than clean beheadings, which regulary happen.
So, I can understand people, who RP ingame that they aren't fond of Aerys' reign. People accept that a King is ruleing stuff, but they get uneasy when he demands absolute controll over areas, which normally belong to his vassals. In the Vale it won't matter too much, because if things go well, Frey gets the Gate for his efforts rather than because the King allowed it. Westerlands seem fine as well, but the Reach got hit pretty serious for just declareing for Maelys. We already discussed that one, as it was a main reason why HB left (though I think he shouldn't have).
In fact it's not a critique, since it's provideing more RP opportunities but don't falls to the same mistake, which I did when I RPed King Robert Baratheon. I was too focused on keeping my own realm in controll that I simply tried to fight any rebellion to keep up the balance, interfereing too much with the plot of other players.
So, never ever RP a King who aims to be perfect.
If you go for absolute rulership: That's brilliant.
Though you should always keep in mind that your character earns what he sows - it's the same with every character, but it's worth mentioning it as no King is perfect.
And that's where things become interesting.
