I’d say a few of the biggest problems are that people teleport and pray.
The reality is that people want to take part in pvp but don’t want to lose their stuff.
In my opinion, the change to the loot system exacerbated the problem even more, because the likelihood of profiting or at least breaking even from pvp for the average player is probably quite low (unless they have a really good kill:death ratio – could you really call such a person average?).

I personally believe that the current death system (ie, die and lose everything) doesn’t really work now that you aren’t guaranteed your opponent’s gear.
With that said though I’m also of the opinion that Jagex would have been better off going down a WoW-like path and using a point system (thus removing looting altogether) as the long-term solution to RWT while still having a pvp environment worthy of taking part in.

In any case death is harsh, and as such people will continue to do what is necessary (praying, teleporting, running) to avoid it. This attitude is as much at fault as the way the game now works, but it’s an attitude that won’t change until numerous large changes are made to a handful of the game’s mechanics (namely death).