With the possible exception of foot infections (e.g. athlete's foot), I can't see that there can be any significant hygiene risks from showering next to somebody else. (The risk of something like athlete's foot would still be present even if you followed a sufferer into a private shower area anyway).
As a naturist I don't care about people seeing me naked anywhere and I fail to see why others should do so.
While many 'council' leisure facilities are actually run by private firms these days, it's still the council that has to pay for structural alterations to the building. Installing private showers would be expensive. While it might meet with the approval of some users, it would no doubt cause a furore among Council Tax payers who would no doubt say that the money could be put to better use. Such major changes to the facilities tend to only come about when major structural changes are needed anyway.
Incidentally, while there are certainly fewer laundrettes than there used to be, the guy who runs the one I use said recently that he could hardly keep pace with the rush. His trade seems to have increased greatly over the pasty couple of years.
Also, there's a long waiting list (sometimes around 10 years or more) for allotments in most parts of the country. Many councils are desperately trying to find somewhere to put new allotments.
Lastly, I still seem able to find plenty of B&Bs with shared bathrooms. (I stayed in one, in Luton, a couple of weeks ago). I'd much rather pay �25 per night for a (beautifully clean) cheap B&B, like that one, than pay twice that for en-suite facilities.
Chris