The JS is just another seat on the airplane like seat 14B is. It's in the company interest to give the best opportunity for guys to get to work without last minute pop up commute issues.
Unless you're #1 you would have to put in a bunch of phone calls in order to secure at least one jump seat. It just seems like a solution in search of a problem.
What does kinda upset me about the nonrev system is that the Express guys are riding around as D2's with us. At Delta they are below mainline employees. I see both arguments but the company has chosen to use our pass benefits as a way to attract people to work at the Express carriers in lieu of paying them more.