The problem arise when there's too much ranged in one team, said team either lose or dominates for the next 3 rounds depending on what the other team has got when it comes to class distribution. It also depends on the map, maps with roofs will always be beneficial for ranged players, for example, Dave and me both went 15+ kills on that map with the two roofs at the center, then proceed to get rekt because there were just too many archers in our team, making us unable to hold all of the cav/melee in front of us.
Then, when it comes to your solution, what defines a ranged player ? Cos anyone can take a crossbow, or at least put some wpf in it. Another issue resides in the level of the players, why should a crossbow main be blocked from entering the server because a level 15 crossbowman is currently playing ?