It's not so much the tagline, as that Polyphony/Kaz are still under the impression that their game is a highly realistic simulator.
Remember the infamous quote around the sound of GT5: "My perspective is that the sounds are just too real."
GTPlanet has released a very interesting exclusive interview with Gran Turismo creator Kazunori Yamauchi.
www.virtualr.net
Kazunori Yamauchi hints at his future plans for the Gran Turismo series, while addressing frequent complaints and questions about GT5.
www.gtplanet.net
That was a problem, because as long as the belief was that the sounds were excellent there was no reason to think that Polyphony would put any effort or resources into changing them in a meaningful way. And in GT6 almost nothing changed with regards to the sounds, bar that they tried to make an engine simulation system for a few cars that was even worse. That mindset clearly changed because they hired an actual professional to manage the sounds for GTS and they're much improved, to the point that the "vacuum cleaner" joke is largely a thing of the past. That's great for everyone, even the people who thought that there was nothing wrong with the sounds before but can enjoy how much better the game sounds now.
There are real issues with the physics of Gran Turismo. Even accepting that Polyphony will sacrifice ultimate realism for playability because that's what their core demographic want, that doesn't necessitate the weird damping physics, the neutered behaviour of FWD cars, the general unresponsiveness to track geometry, and probably any number of other things that people more knowledgable that I could go into. Arguably the game becomes better with these things, because while a proper implementation doesn't really raise the skill floor they absolutely raise the skill ceiling.
Something like Assetto Corsa isn't really any harder to drive for a novice than Gran Turismo (bar the fact that Gran Turismo has far better pad optimisation, but that's not a physics thing), but there
is a lot more room to develop your skills as a driver. That's why you get the "hardcore" crowd pushing back against the idea that the physics need to be the way they are for the casual crowd - it's just not true. This is one situation where you can have your cake and eat it too.
The tagline itself isn't a problem, but it is a symbolic representation of the problematic mindset. While the physics in GT has improved somewhat over the years, the idea that it's a realistic simulation is damaging in the same way that the idea that the sounds were too real was damaging. It removes any impetus to keep pushing for something better.
Kaz has espoused in interviews in the past that he thinks that good physics should be easy to drive, and he's not wrong. The whole "harder to drive is better" thing is a holdover from the early days of hardcore sims where that kinda-sorta was true, because it was arcade games versus sims. But modern sims like AC or rF2 or even iRacing are not hard to drive. They're hard to drive
fast, but that's true in real life too. That's why racing drivers are professionals who train and dedicate thousands of hours to becoming proficient at their craft. Anyone can go to an open day on a track with their own car and expect to very quickly be able to go around it at speed without plowing into a wall, you'll just be multiple seconds a lap slower than a professional would be.
I'd like to see GT become as realistic as it can be without alienating players, because that's a big part of what it presents itself as. I think that's a lot more realistic than it is right now, and is a far bigger step than we've seen between any two GT games with the possible exception of GT2 to GT3.