Simple economics would be my guess.
If they were selling enough of them, and turning enough profit, they wouldn't quit making them.
There is either:
1) Not enough demand at the price they can sell them for.
2) Not enough profit at that price.
They do make really good equipment, but I think the Logitech MOMO wheel really hurt them in the racing division.
It is not as good as their stuff, but is a whole lot cheaper.