My stance on this is quite simple. They do not provide any benefit to the game-play, and actually hinder the purpose that push has provided.
The premise is pretty straight forward, you spawn you capture zones in a series and will eventually collide with the enemy. Upon this collision occurring - you begin a back and forth battle that will ensue as long as sides have lives to spare. It is a logistical battle, in that you have to make sure that a) you don't die, and b) that you don't run out of ammunition which both may lead to loss of your foot hold.
Adding mobile spawn points may seem pertinent to your map, but in the whole they do nothing to aide in our game-plays needs and in fact remove the two reasons that push becomes more thought driven than just running and gunning. If i know that my life has purpose i will not waste it. Dying currently has a dual penalty - you will leave the battle at its current location, making it easier for the opposition to move forward and overwhelm your brothers in arms, but it also penalizes you with an extended period of time until you can return to battle. If spawn locations are close to the currently fought over zone you are in effect making it useless to play this as push, and providing a new game mode entirely to itself.
In regards to your comment about the maps needing to be square you are incorrect. With creativity in your hands it will not be difficult to devise some maps that provide numerous routes to many locations and in fact are not square at all. Many maps in Firearms were not square, and FA was entirely Push. Many maps in Battlefield and many other games that are territorial based are not square. It just comes down to your, or others, creative talent to be able to devise a map that is not simply a square. It couldn't be too difficult, because i have seen it done many a time. Our current Push test map is not square. Territorial lends itself to symmetric maps but that is not a necessity. We have already provided the means for you as a mapper to provide a score to the volume that you place in game to control the reward for holding the zone. You could put two volumes near one base each worth 6 points and another around the corner from the second base and have it worth 20. You can scale them as you need, and depending on the actual needs of the map you may find it useful to do so.