Pirelli has a "super soft" compound slick tyre which is sometimes used in Formula 1 races (not just qualifying), depending on the circuit. So why are people saying the RS tyres are "unrealistic" 
look at the speed they take corners. Check R1600Turbo's video for example, in which he used Comfort Softs. Not sports softs, not racing hards, Comfort softs.
I know it's been said lots of times, but the tires that were made having proper simulation in mind are comfort softs (or meds can't remember).
In the end people who defend RS tires to death are the ones that prefer the arcade style physics those provide for every car instead of trying the game the way it should be played. I understand that's a personal choice to make, but add RS, ABS (with its hidden stability assist) and people using a DS3 (more assists) and it ends up in 99.9% of players not playing the game.
Racing tires as a whole literally killed GT5's simulation. GT6 should simply be like proper sims and have simply one tire for each car, 2 or 3 at most and even then those are on the same "category" (so if it comes with sports hards then you can buy up to sports softs and not more). It's either that or drop the driving simulator catch phrase.
But banning race tyres to be used isn't going to solve that, it probably just means a lot of people aren't gonna play GT5 anymore (which would have the same result basically as filtering online options since only a minority is left) or a lot of people entering rooms aimed for 'pro's' without the expected level of skill.
Just because you prefer to drive roadcars with road tyres, doesn't mean everyone should or is even able to do so (maybe some eventually will but GT-games have a steep learning curve).
And that second thought isn't very consistent with the rest of your reasoning, if it was it would mean dirt tyres being only available for rallycars for example.
Another thing, if you apply full weight saving stages, chassis reinforcement and add all performance parts available to a roadcar in GT5, it already isn't a 'real' roadcar anymore since I doubt most tuning firms in real life can reduce the amount of weight of a roadcar to that level without stripping most of the interior so most fully tuned roadcars in GT5 are basically racecars appearing like roadcars.
Or do you want to stop being able to tune a car too?
I wrote that those changes should be made for GT6, not GT5. A 1 and a half years old game simply shouldn't receive substantial modifications.
It's true you can do all that tuning, but that's true for real life as well. Thing is as far as I know no one fits $36,000 tires to a $5,000 car, for several reasons.
In the end there are 3 different topics to discuss: Removing RS tires, which tire types are allowed for each car (to stop having 350pp cars fitted with racing tires), and if driving aids should be allowed in every car or not, as someone suggested.
About the last one, and this will be the last edit to this post lol, I think they shouldn't. It's unrealistic to drive a 60s car with ABS, traction control and what not, to the point those assists kill the whole purpose of driving one of them: the feel of not having total control over the car, lack of traction, etc.
if you are a Sports Hard / Comfort Soft racer like me 
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. And even so I don't do it often.
