As long as we're talking change requests, and we have swaMark's attention - For the love of god, please please offer the ability to store passenger profiles!
I travel a lot on SW, with my family. Yet the website/app is incapable of simply storing the name, birthdates, RR number and Trusted traveler info of my wife and kids. I'm forced to enter and re-enter all of this info dozens of times a year! I love SW, but most other airlines offered this functionality in the 90s! Sometimes it seems like I'll spend more time booking a flight for my family than I spend flying it! I'd think SW would want to make it easy to book tickets, right?
A distant second would be the ability to select travel funds you want to use, rather than have to open another window, browse, copy and paste the one you want to use.
/rant