Well, not sure if you guys ever set AFK Stalls, but it feels great to simply stall stuff with an alt and not having to worry about re-opening, DCing, or having that extra client around while the character is stalling till everything's bought.
But yes, it does have lots of downsides. For instance it's very hard to find what you're looking for in the complete mess of stalls, and honestly the city is just too crowded with them. There's also the fact that you can pretty much lvl your pet much more easily. (Which is actually better for the PC, rather than the player)
I really don't see how making stalls close after a set amount of time would really solve anything. I believe most stalls are set by people who are actively playing or at least wouldn't mind re-making a stall every now and then. I doubt there's people who just made a stall for the lulz which doesn't intend to close by selling out nor by the player.
Although I strongly agree with adding something which would make those afk stalls more bearable, a time limit wouldn't really do a lot in my opinion. The Ctrl + S option, which hides stall names, was a step in the right direction imo.