I can't for the life of me see why people are objecting to the scheme. Sure it's open to abuse but so are many things. Generally, most people as far as I can tell use it in the spirit it was intended. If airfields were being inundated with dubious diversions then I'm sure they'd be making it know to the powers that be.
The decision to divert will take into account many issues, by offering free landing fees for diversions it will hopefully remove one financial consideration.
We can all bleat on about how 'we' would always divert rather than risk skud running home in marginal conditions, however there are people out there who will press on if they think it'll save them a £30 or £X landing fee. If it helps them make the sensible choice and prevents an accident then I would hope I'm not alone in wishing the scheme continues for many years to come.