Dual spec doesn’t fix an issue, and it goes directly against the intended design goals of tbc, which tbcc is emulating.
It also removes consequences of choice, devaluing the rpg element of the mmorpg.
Dual spec changes player behavior more towards the arcade version that retail is, defeating the purpose of a classic game by letting choices have far less impact, which will lead to a meta shift that will impact every player, even those who chose not to get dual spec.
On top of the fact that the reason you want dual spec boils down to “my gold bro!”
Play the game and you have plenty of gold, aka stop raid logging.