I've had the misfortune of flying on US CRJ200's twice a week almost every week this year. My first few flights on them I chose exit row seats and found no additional seat pitch whatsoever... I'm 6'3" and found it nearly impossible to open a laptop to get any work done or to reach under the seat in front to get something out of your bag. Also 8A/F don't have an armrest.

For what it's worth, my favourite seats are by far 1C and 1D. The lack of a seat in front is helpful, but even better is the fact you can get out of there as soon as possible...

To address OP's question directly: I've never seen Exit Rows coded as "Choice Seats" (which are the paid seats even for elites) so I'm not sure why you're seeing it that way... the only thing I can think of is codeshare issues.