I just loved the B-Spec aspect in GT5. I worked 24u shifts at the time. It was just perfect. Just before i left for work, i put on a race with my bob and when my shift was over and i got home, my driver finished the race in first place and i got a bunch of credits and especially back then, grinded points towards reaching level 40 (or was it 50?) for B-Spec.
You know, the AI and how your driver race against that AI is just not the problem. PD took a decision with GT7 to implement MTX (worst decision ever) and i just don't see it how they would implement B-Spec in the game with the right balance of earning credits with B-Spec. I don't know: do you see your bob racing at 30' Le Mans for the same amount of credits? Maybe some people, but personally i would rather race a 30' minute race myself.
Then there is the fact that currently there are no real endurance races in the game. Now, "if" B-Spec would come to the game does that mean that they will implement it with the addition of endurance races at the same time? Now how would that work? A 3.0 Spec update? Or will they add endurance races before B-Spec? A normal update gives us 3-5 new races. To use B-Spec at it's full potential i feel like we would need alot of different endurance races. Aka: 2/4/8/9/12/24 hour races. And then once again the question: what about the credits earning for such races? Maybe they make the decision that with those races you can only earn credits once? What absolutely would destroy the purpose of a having a B-Spec mode in my opinion.
Apart for the content update model, no endurance races in GT7 is my biggest frustration. We have such a fantastic game with variable weather, many cars to race but apart from custom races no option to play pre-set endurance races. And the 1 hour "endurance" races were a very nice addition and some of those races are challenging, but personally only able to earn credits once made me never touch those races again.
So B-Spec mode, yes please! But hopefully implemented with the right choices from PD in favor of the players.