I still see it as a useful feature, but ultimately the responsibility falls on stakeholders to use it properly - just the same as witness voting.
There is danger of people who just "proxy and forget" or cases where a proxy uses their power in ways that the users who trusted it to them would disagree with. If people are going to proxy their vote to someone, it is my view that they need to take the responsibility to at least periodically monitor and check in with their proxy.
I mostly agree with this but I would definitely include proxy setting in the "lost account" expiration feature. I suppose one could make the case it should have a longer lifespan, but still should have some lifespan shorter than forever.