Well as you know, any melee-centric character is going to be a target. The only reason assassin class in any game survive is because of the tools they're given to do so, stealth is just one of them. A non-stealth melee burst class can be given any number of tools to improve their short term suvivability: shields, heals, debuff mechanics, mobility. From a more practical perspective, ranged DPS is the single best way to burst another character down. Use the terrain to your advantage, hope you're not seen, hit with a big opener then snare, snare and kit until they're dead. I did this countless times from bushes or the water in WoW with a Marks hunter in TBC, and saw it done endlessly with Fire Mages as well. As I said, players just love the stealth+burst archetype and are loath to give it up, even if that means that PvP combat could be balanced more easily. I don't blame players for loving it, as its insanely fun and satisfying, but permanent stealth is a difficult mechanic to work around at best and is anti-fun at the worst.