I love shutters too (great night’s sleep with the darkness).
I think their lack of UK popularity is due to many reasons, but the ones that seem the most likely to me are:
(a) most UK windows open outwards (and so you cannot shut/lock shutters from the inside. I’d be interested to know which way Scandinavian window design went).
(b) people who like shutters for aesthetic reasons are more likely to dislike uPVC windows (v.large generalisation!) and most reasonably priced continental shutters are roller ones (e.g. plastic or metal)
(c) because you do need permission if you put them outside the house in a conservation area.
I’m putting shutters on my house (French partner) and consequently am going to go the internal shutter route to get around two of the above.