Interesting to read. I agree it's essentially a "pub vs comp" problem, but have a few rambling thoughts...
Different classes need support from other players/classes to different degrees in order for their abilities to shine.
By its design as the main front-line defensive class the soldier needs to be able to cope to an appropriate degree without direct support surrounding him. Taken in isolation the soldier may therefore appear too powerful relative to the other defensive classes, but when used together to support each other as a team the other defensive classes can be significantly more powerful and more important to the defense's success.
Given the above plus that the game is most fun when players work together I think that anything we can do to encourage players to support each other more in public play would be great, especially on defense. For example, how about every time a player scores a kill every team mate within a fixed distance of them also scores a kill (or assist)?