Part of their issue though is that by continuing with the title as an entry in the "Project CARS" series, they are fighting some preconceptions right from the moment someone reads the title. For right now, it might be a vocal minority, but things might change when the game is released.
A lot of "average racing gamers" that play things like Forza and Wreckfest and Dirt games or whatever, did not have good experiences with PC1 and PC2... You can see it everywhere, and from my own experience I've seen it as well. I help organize a league on Forza that has 20-30 players a week and total community of 60-80 or so over the times that PC1 and PC2 have been out, and I tried multiple times to get something on PC2 running with them, but only about 4 of them liked it at all... and it's maybe telling that all 4 of them have since gone onto PC and iRacing.
You are right that average racing guys aren't likely overly bothered by the exclusion of pit stops, and most of them don't know the difference between GTE and GT3 anyway to be bothered by the mixed fields and so on... But a lot of those average racing guys don't follow all this preview and forum stuff closely, and possibly aren't going to be giving PC3 much of a chance because they will be expecting a more hardcore, buggy game that doesn't work well on a controller, and therefore aren't likely to be buying it.
Alternatively, the more sim-leaning guys that don't follow these previews and forum things might buy the game expecting more PC2 and be horrified when they find no pit stops and '70s Ford Escorts rear-ending their GT3 car, and it could lead to a flood of poor user reviews and likely some new members on various forums and Discords showing up and yelling "WHAT THE **** I THOUGHT THIS WAS A SIM!? I WANT MY MONEY BACK!"