Honestly, I wonder how much better it would be if more of the Sport Mode races in general, including both the daily races and FIAGTCs (sans the Manufacturers Series) were just one-makes, making them more of a driver's competition rather than a matter of picking/having the right car. I think that's why I usually enjoy Race A so much. On top of this, I'd really love to see more groups in the Manufacturers Series than just the usual Gr.3 and Gr.4, even if it meant the possibility of some automakers being omitted while others are added.
I just like how in the Manufacturers Series, you see a much more diverse field of cars, because you're effectively locked into the cars you picked for that season/stage. Heck, I wouldn't even mind if they did something similar to F1, where they merge the Manufacturers Series and Nations Cup into a single championship, much like how F1 has both the drivers and constructors championships going on simultaneously, as I'd compare the former to the Nations Cup and the latter to the Manufacturers Series. In this regard, you could even be forced to select some N-Series machines, maybe even multiple depending on what N-Classes are going to be part of a given season.
I also could see why PD wouldn't want to have BoP go on a race-by-race basis - that'd be a ton of car/track combinations to test. I'm sure if solely using AI to test cars was a realistic option, without any human driving/testing, they'd do that.
EDIT: I sincerely believe the issue of just picking meta cars would be solved if more races were either one-makes, or worked more like the Manufacturers Series, where you're locked into a given set of cars for some time. At any rate, I'm hoping PD is taking tons of notes from the various Sport Mode races - as well as the various championships - as I think ranked online for any game is a great way to collect data on what's popular, and what may need buffs/nerfs. Just look at Pokemon, for example: the ability Prankster was very popular from its introduction in Gen V, and in Gen VII, it was nerfed so that a move that had its priority boosted by this ability would fail if used against a dark-type species. Another example being Leech Life, which was a complete joke of a move until Gen VII, where its base power was boosted four-fold!