There are times when the hitscan wins handsdown most of the time, as in wide open areas with barely any cover. This can lead to very unbalanced matches of hitscan vs. projecitle. However, you should blame the creator of the arena who made the build with such flaws that enabled the hitscan user to gain too much power.
Bushido has mentioned ways that he has countered the hitscan's advantage script wise. I don't think the hitscans are out of place. Just learn how to properly incoorporate the hitscan weapons. Although, the pistol, I don't think, needs much consideration, the sniper should have disadvantages, arena wise.