First of all, Subaru never "failed" with the TR because in 06-07, a large majority of the WRX's stocked at dealerships were TR's and not standard WRX's. In fact, I saw more limited WRX's in my search for a car rather than the standard model at the many dealerships I visited or searched online.
If you look back using the search feature here or on NASIOC, you will see many posts that refer to the only WRX's physically available on the lot were TR's, during that time period.
And there are a lot of TR owners here on the forum. But, yes, I do get your point that the TR is not in the true sense a race-ready car, much like the radio-delete musclecars from the 60s.
As far as "low-quality", we all must realize that there are no low quality parts on a Subaru, in relation to one model to the the other. They are all sourced from similiar suppliers. So the suede seats in an STI are certainly of more value, but to say the seats in a TR or an Outback are low-quality is not correct. It's just a matter of cost. I figured this was what was intended in that comment, correct?
The single CD radio in the TR is just as good quality as the 6-cd radio in the WRX or STI, just not as costly from a unit price standpoint.
The side mirrors are the same material, just one is painted and the TR is not.
The seats are one interesting characteristic between TR, standard WRX, limited WRX, and STI. While I actually like the feel of the TR seats, I too would like to upgrade. But racing seats, like Subaru predicted we would go to if we bought a TR, can be very expensive, require additional mounting hardware, and lose the side airbags. So most who upgrade go with the STI interior swap. I can't because blue seats look like crap on a red car, but you get the point. Now JDM seats or STI limited seats are all favs, but really expensive, when you compare to using those funds for the engine, tranny, or suspension. And, myself, I've never actually heard of a TR owner swapping their seats for standard WRX seats (although I'm sure some have).
But, in conclusion, I do agree to what has been said, but please consider that at the point of purchase, many of us Subie-lovers didn't have a whole lot of choice on the dealer lots in regards to Standard vs. TR, if we wanted to buy a car off the lot (at least in my geographical area)