Personally I found that this game was a great mix between a hardcore military simulator and a fps game, so naturally I leaned more to the non hardcore servers.
You make a very good point about newer players not exactly knowing the gamemode, very often I myself, and other new players would accidentally shoot allies on hardcore servers.
Of course, the solution is: to play on NON hardcore servers. I'm disappointed that the "casual" servers are in the minority in comparison to hardcore servers.
I think it'd be cool to see more servers switch to "casual" mode. I guess a more balance of 50/50 would be fair.