The new, $10 charge for early boarding, was done for revenue. It doesn't really do anything to improve the boarding process. It does make some sense to offer lower BP numbers to passengers who pay extra rather then to passengers that are willing (and have the time) to check in at T-24.
Correct, it does offer some convienience to those that dont want to mess around with t-24, but it obviously was done to generate $$ without 'changing' their fares etc.
SWs (initial) success was (in part) due to their ability to turn around the planes quicker then other airlines. An airline on the ground doesn't make money. Quick turnaround allowed SW to schedule an additional daily flight per plane. Lack of assigned seats motivates passengers to get to the gate early and to be ready to board early. Passengers with assigned seats are more likely to wait until a few minutes before the flight to board. I'm not sure if the current "fighting" for bin space has changed those assumptions.
Even with 2 free checked bags, you still have problems with over head bin space. And this isnt just to / from MCO. THere are just some folks that have carry ons that are just |--| that much too big to fight 'front to back' Granted, I've seen it close to having to gate check, but they always make room. I agree with the people arriving early for the flight, I dont know of any flight I've done with SWA in the last almost 2 years that we had a straggler come on the plane.
Assigning seats gives the "best seats" to leisure passengers who book low fares months before their trip. Profitable business passengers, who book days before the flight, wind up with "left over" seats. Legacy airlines deal with this by blocking seats in the front of the plane for elite passengers and passengers who pay full fare. This complicates the seat assignment process and would result in SW passengers complaining about being "second class" passengers.
SWs present system allocates the first 15 BPs to passengers who pay extra for business select and the next group of BPs to A-Listers (frequent fliers).
Most of the "problems" only exist on internet boards.
That's a very true statement. 
Passengers are willing to switch seats so a young child can sit with at least one parent. This happens when a family is late to the gate and misses family boarding. Traffic. A flight delay which results in a tight connection.
I 100% agree. People that say they wont consider moving to allow a parent / child to sit together probably do exist, but I bet for those that say they wont move, there are others that will gladly move or try to move at least.
I suspect a lot of older kids (7+) don't mind being separated from their parents. They don't (generally) behave the way parents on the internet threaten us. Last time I had a child in the middle seat next to me he spent the entire flight doing homework.
Heck, everyone I know says I'm just a big kid anyway. If we were lucky, they'd have a DS or something that you could multi play a game together lol..
SW now has one GA servicing multiple gates and multiple flights. Airlines that assign seats hold some seats back for gate assignment. SW might have to increase staffing to handle those seat assignments.
I don't really understand many of the posters. AFAIK SW is the only major airline that doesn't offer assigned seats. People should book an airline that meets their needs. Be willing to pay the extra charge for assigned seats.
Again, I agree, I've had NO problems with SW boarding, BUT I'm one that does it exactly at t-24. Worst I've had on my initial flight was A-22 when we had some a listers in front of us (behind the bus select) and the worst I had on the connecting flight was A-32, where others started their flights before I did. IF it appears this is going to put me 'too far down the line' in my opinion, then I may look at another carrier, but I've been perfectly happy up to this point. And if I use the EBCI and dont get a decent BP# or am not happy, again, I can and may look at some other lines.