The Gran Turismo games, namely the later ones, are pretentious in the fact that the director of the game, Kazunori Yamauchi, is the main driving force in regards to the game design decisions for the games, and is even moreso than other games in general. And while his sheer dedication to the franchise has led to massive changes in the racing game genre, such as "realistic physics", car licensing becoming more and more commonplace, and pushing graphics to the maximum (which has both it's good and bad points), the later GT games had strange design choices that you wouldn't usually see from games in other genres, and other racing games would follow some of those said trends to the detriment of the genre.
The decision to include PS2 and PSP models in GT5 and 6, just so they can brag that the games have over 1000 and 1200 cars respectively, and the older games having various trims of the same car, comes off as padding the game. Although other racing games are also guilty of re-using car models for too long, i.e. Forza Motorsport 2023 still having models from the original FM game.
Gran Turismo 6 added the Vision GT concept, to get auto makers to design futuristic looking concept cars, which the community is mixed about their inclusion in the games. GT6 being a PS3 game, even though the PS4 was just released, was also a massive missed opportunity, as there wouldn't be a PS4 GT game, until Gran Turismo Sport released in 2017.
GT Sport was design specifically to cash in on the E-Sports trends at the time, although I don't remember if it's either Kaz, or Sony, that pushed for it. The game also served as a reset of the series, going from the 1200+ cars in GT6, to only 130+ cars on launch, and 338 cars at the end of the game's life, to push for the improved graphics on car models. Scapes were also added, which is part of the trend in racing games to push hard for Photo Modes being a key feature, which is a small part of the game that tends to get too much focus on by game developers, just because.
Gran Turismo 7, despite it being said as a "return to the GT games of old", had numerous issues with the game, and didn't feel like a return to those said older GT games. The fact that the game has Hagerty sponsorship for the rotating Legendary Car dealer, and that those said car prices would change to "reflect IRL trends", meant that Kaz decided to put inflation into a video game too, as if people weren't sick enough of having to deal with skyrocketing prices IRL on everything that they buy. GT also had a movie made too, although it's more because Sony wants to make movies and TV shows out of all of their video game IPs.
The pretentiousness would also spread to GT's community too, as some people are way too obsessed with the game, and defend the game as if Kaz's holding them at gunpoint. They brag about GT having the best graphics, the best physics, the best multiplayer racing, and trash talk other games for being inferior, even if GT has those same said flaws. Some also like to compare GT with Sim Racing games, and Sim Racing is a massive rabbit hole in itself. Whereas with other racing games, their communities tend to be more self-aware of their games's flaws, either accepting those flaws, or uselessly whining loudly about them.
