I think also that its a way of income.
There are not many attractions in the flatlands of Belgium that draw tourism. Its not pretty, its not full of widely relevant history (unless you are into war history) its a bit like the isle of Thanet, sure there is stuff to see but its more like a stop over than a destination.
So cycling has put many towns, villages, hills and entire regions on the map, attracting tens of thousands of visitors for a single event.
Flanders, this weekend has something like 60,000 participants...all renting accommodation, buying meals and enjoying/recommending the region.
It feels like parts of the UK dont want this added attention and feel that they do just fine by using their thatched cottages, cathedrals and beaches to attract tourists, without having to shut it all down for a bunch of mamils.