Career was a lot of fun, but I feel like picking different options won't really change that much.
There are still eleven disc songs I haven't played somehow.
Yeah, the career stuff was a letdown. Money was almost never in short supply, and I preferred playing the premade setlists instead of the voting ones. But that locks me out of the special gear unlocks.
None of the choices really felt like they had an impact, and it just feels like a missed opprotunity. This could be a really interesting mode, if they fleshed it out. Have a deeper on-disc library to play with, and craft a narrative where you can really shape the outcome. Imagine having to decide between doing a tour of profitable teenybopper pop songs to fund your dreams of a tour where you exclusively play hair metal and prog rock.
Allow that cash to purchase in-game upgrades, like a bonus to Overcharge duration. Bring back the tug-of-war mode, and go head-to-head with rival acts. Give the player control over the band's branding, and reflect those choices in a meaningful way.
I hope that if this franchise kicks back into full gear, Harmonix will spend some time really fleshing out the possibility of a campaign. Make a full game focused on that one element. Could be amazing.