Would be a nice feature to automaticly install mods needed for servers. There is already a lot of stuff out there and there will come even more like in ARMA2.
A problem is, you always have to start Arma with a launcher for every server that uses content mods. Or you have to activate the mods, and restart Arma. If you want to join another server, you have to do it again.
I mean if you just add a new vehicle, nobody can join the server without installing the right mods especially for this one.
There should be a way to to make this easier, because a lot of small mods (like single weapons) will never be used otherwise. Just the really popular modpacks will have a chance