I don't have any first-hand knowledge, of yours or of any other airport operations. But I think there's a genuine concern over the "weather diversion" being exploited unfairly.
One of the essential parts of pre-flight planning is Plan B -- what I do when things don't work out as I expect. Weather is one of the most common spanners in the works. I should take account of the possibility of the need to invoke Plan B in the decision as to whether or not to make the flight. If Plan B includes landing at a more expensive airport, that's part of the cost of the flight.
That said, and human nature being what it is, pilots will undoubtedly let their in-flight decisions be influenced by the cost of diverting, and if the scheme helps pilots to stay alive, that's got to be good. I just wonder if this is a case of good, prudent pilots subsidizing bad, careless pilots.