Here's what I think:

Not enough people are playing PvP and the incentives they keep adding (minions, mount, gear, etc) is only a temporary fix. From the looks of it, the devs have no intention of making PvP as hardcore as people want them to and the recent patch of making casters and healers easier to play further proves this. The devs want people to have an easier time to jump into PvP and hope that they stick around. The addition of tomestones was a thing since Wolves Den was created so that people had an incentive to PvP. If you make it where getting tomestones can only be earned by winning, I can bet that less people will be willing to try out PvP or stick around for it. Logically, you shouldn't get anything for losing, but due to the nature of DF players, I don't think anyone would enjoy losing due to their incompetent team and having nothing to show for it. You think it's bad now with newbies ruining ranked matches? It'll only get worse if you make it where items can only be gotten through victories.

I tried the feast as a brand new PvP player and while I had my share of fun, I am quickly losing interest since there's nothing else go for aside from glamours and I'm sick having teams break into a hissy fit the minute things go wrong. What PvP needs is better incentives and longer lasting power, not less incentives.