+1 Internetz for this idea, just make sure that only the mappers have the ability to set spawn points
I harp on this alot, but giving the squad leader the ability to make new spawn points is the worst idea with the best intentions. Enter-> Killzone 2 multiplayer, where spawn points are made 3 ft from the objective by both sides and at that point the game becomes unplayable and unenjoyable
The main idea about squad leaders, was a bit different though, it wasn't them randomly clicking on a map and letting the team spawn there, so they cannot "create" spawn zones. Imagine you have small squads with squad leaders being regular soldiers. Like a team got say 5 little squads of 5 people. (Where the current weapon/arty class of squad leader gets renamed to platoon leader).
Then every squad leader of those small groups can select where his squad spawns. However not randomly on the map but he can select where to spawn out of predefined spawn locations that the mapper made. With as primary idea that squads just spawn together, rather than scattered over the entire map.
Beside that mobile spawns like a halftrack or whatever if added would only be an additional tool for mappers, they wouldn't be forced to use it in every map. For really huge CA maps having a mobile halftrack spawn could be quite interesting. (Think of alte ziegelei for instance).
How squads would be formed, how squad leaders get selected, and what the min size of a squad would be, would be up for someone else thinking out how squads would work the best in general. But spawning together with a smaller group like a squad, makes it a lot easier to communicate and work together than when every person on the same team is just dumped into 1 big group.
If squadleaders could talk with other SLs they could decide to say both attack the right flank, or one the left and one the right flank etc. It allows for some more tactical options.