People have been acting as if a TR on a TP aircraft is a one-way avenue, but surely if you have a full ATPL and enough hours under your belt, you can still go and get another TR further down the line
It's more that when you go on looking for other jobs down the line, TP is nowhere near as valuable as jet time, so a 737 or A320 rating is far more marketable for future employment.
But it's a job, and the rating comes with it, so I wouldn't be moaning.