Honestly? Yeah, I would prefer that. Using the original spawn in some maps is not a big deal because the distance to the objective/any line is not that far, but on some maps it can make the difference. I guess that's what it was planned for, making a difference if used correctly. You may argue that this is what an officer commanding the line should do, use it correctly. Probably fall back to "rally" and letting people spawn in relative safety and then to attack again/countercharge or whatever. I guess that this will work, but only in really well organized regimental events. On public servers it probably won't.
Would it be an option (that also means if it was practicable in first place) that the flag bearer has to define a spawn location/zone? Probably in a similar way officers can draw lines? I know it would be a very gamey feature I guess, but to be honest the flag bearer already is less on the realism side of things.
I don't think it would harm the game if flagspawning on both sides was quicker, may it be by faster spawning times or spawning in larger groups.