The paywall "whiners" are doing a public service - a single paywalled article from a popular poster can waste the time of thousands of people. If I see "paywall" I can adjust my expectations and decide if It's worth the effort or I should just move along.
I'd honestly rather see an automatic paywall indicator as part of the client, but that may be infeasible - the client would need to know which sites the user subs to and it could be a headache.