Just a twist, but isn't one of the popularity of folding bikes in the UK due to need to respond to the abysmal rail transport / urban / office infrastructure of moving a bike and storing it somewhere safe?
I have been impressed at the army of commuters leaving London with their lunch-box sized bikes to neatly store on the train, and then ride off from the station to home. But....
Now compare this to other major cities across Europe, and you will find a normal bike is generally sufficient due to the supporting infrastructure.
If you've been to the pinnacle in Holland, then you know what I'm talking about to see the direction I'm coming from.
My mother rode a Moulton and it fell to bits and she ended up in hospital; anything with fastened joints will never be as trust worthy as a welded frame. That's a hard fact to dispute.
In my youth, one of our lecturers gave a speech how fast and stable his Moulton was and how he could corner faster than anyone else on a "normal bike". I pointed out TdF riders regularly approach the 50 Mph mark and his response was "...because they leave their brain at the top of the mountain". Mmmh. So much for the science of cycling.
To be clear, I'm very hesitant of there cycling quality and remain to be convinced, but don't doubt they have a significant practical use in day to day functions with certain constraints of space. It is a compromise.
By the way, I think this example from the OP and it's price tag is just stupid. I'm using a parts bin SS special for commuting, no big loss if it's stolen or wrecked and would happily attempt to thrash anyone on an expensive folder in a catorgary 6 race with it (up hill or off the lights or on the deep pothole routes of course)