We all know that all custom maps can only be played unranked. If this changes, a much bigger community will appear.

I don't think this will ever happen cause of security reasons.
Unless, Crytek decides to take the time and approve a map and then make the server ranked.

The whole rank thing is a gimmick anyway, it's basically just "who's played longer" because playing longer = more exp and has nothing to do with skill. I'd be happy if they just removed it altogether (the experience system)

I also thought of the approval thing, sounds perfect, but considering how they fail to manage a community, let alone map approval.

Oh and also add an auto download. Most people didn't play custom maps because they don't know where to find them

Well if you see it that way, instead of earning experience for kills, why not just earn experience for perks of weapons you use?
Also, there could be a seniority rank, like the longer you play the higher your rank goes up.
This can show who the veterans are and who are the most dedicated to the game.