Now, as an avid flag builder, on of the most frustrating and difficult thing to do in this game is plant a flag. Both teammates and enemy will destroy your hard work in seconds, and the glorious sight of seeing a the colors of your nation fly over the enemies territory should not be impossible to achieve.
So, I must suggest flags! Maybe you could give a certain class a flag instead of say, grenades, or just add them in altogether. What's the point of it? Well, nothing. It would just be entertaining to plant your flag on top of your creations, something that doesn't tumble in a gunshot.
And perhaps if an enemy hits a key on your flag, it turns their color to signify capture! It's pointless, but a fun, light hearted suggestion regardless. Does everything need to have a purpose?