The music was awesome. They HAD to get rid of the trumpets, they got so annoying. Gen 3 had some of the worst soundtrack in the series (second worst only behind X/Y).
The story is way more fleshed out in ORAS, the evil teams, Brendan/May, and the evil teams got their due. It makes R/S feel like it has an incomplete story by comparison. At least it actually had an adequate story, unlike pokemon X/Y. The game is made for 10 year olds! Most of the games are about saving the world as the chosen one. How is ORAS different in any regard?
Are you talking about Mirage spots? How is that a con? Don't go catching them if you dont want to, you're not forced to do it.
ORAS has more fleshed out secret bases, the dexnav, rematching trainers, sneaking mechanic, and more which none of the 3DS games ever had.
Giving you a free Latias was stupid. Though thank god it didnt give us a free gen 1 starter an hour into the game and lucario as part of excessive fanservice.
Let's just start this post by clarifying that your musical taste is truly atrocious.
"The story is way more fleshed out in ORAS" yes it is, and that's why it's bad, because it's written like fucking shit. If I'm cringing in every cutscene, and cutscenes are going on all the time, then something is wrong. Yes most Pokémon stories have you saving the world, but there's rarely a "chosen one" element to it - and when there is, it's like, once. In Black/White you were N's chosen one to face him at the end of the game. In X/Y you were Lysandre's chosen one to stop him. Even in these occasions where you were someone's "chosen one", you were someone's chosen one, and that's already a lot better than being the "chosen one" just because. In OR/AS, you are the chosen one for:
1. Pokémon Contests
4. The Pokémon League
6. Rayquaza/Zinnia and her people
Literally all of these things are forced onto the player, with no choice. What it creates, is a game that's constantly telling you who you are, rather than allowing you to just be yourself. I think that's most epitomised by the game's baffling decision to remove character customization. OR/AS is all about forcing you to do things you don't want to do, and then telling you quite explicitly that you do want to do them. It's just fucking annoying. When I was first playing it (well, I only played it once), that whole Latias/Latios segment halfway through the game was pretty much the biggest turn-off I've had in Pokémon - I don't like having legendary Pokémon on my team, and I don't like being forced into catching them. It's understandable when they're the main cover legendary and you know the story will revolve around them, but forcing me to stop my adventure literally halfway through it because some random legendary I don't give a shit about wants to be caught by me was a fucking insult to me as a player.