I am a Scoundrel and I do use Dots to help prevent capping. I think a few things need to be cleared up though.
First, can the Dots be cleansed or not? I always thought that they could by cleanses that cleanse physical effects. On the Scoundrel board, I have read that Dirty Fighting (DoT Branch) can be made ineffective by one cleanse. IMO, if they can not be cleansed, then I do think that needs to be adjusted so that they can be cleansed. If they can be cleansed, I do not see a major issue at all.
Second, do shields prevent you from being interrupted while capping? If so, is this not a similar issue but in reverse?
Third, Dots really are not that great in PvP as I am sure everyone knows. I rarely used Vital Shot until I learned that it prevents capping. I am pretty sure that I have had people cap while dotted, so I had thought that there were good counters to the tactic in place already.
I would prefer that viable counters are implemented to add more stratagy to WZs instead of just taking away this tactic.