Why do all low profile tires have to be of high performance design?

[grampi]

Maybe there are some tire experts in here who can help me out with this one. For the life of me, I can't figure out why all low profile tires have to be either H, V,W, or Z speed rated. Why can't tire manufacturers make 50 and lower series tires in an S or T speed rating?

There seems to be quite a few people in this forum who like the looks of the low profile tires, but they hate the fact that 1) they have to pay a higher price to purchase these tires because they are high performance tires and 2) the compound these tires are composed of is so soft they just don't last very long. In fact, if we were to take a poll, I would bet money that more people would rather have these tires available in a high mileage compound than in a high performance compound. At the very least, they should be available in both forms.

Is there some ligitimate reason why these tires couldn't be made available in an all-season, 80K mile touring tire?