IMO the huge hashrates being provided by proxied pools using WP as a backend are the problem and only improve profit for PW but not the dedicated WP miners because they take large amounts of shares away from us ... much like what ASIC are doing to scrypt.
Its just more hash-power, its bound to happen for every algorithm. If they weren't mining X11 on WP, they'd be mining X11 somewhere else, and having the exact same effect on WP.