The fact that a size is defined as a standard, doesn't mean that there are components available.

If you have a bike with ETRTO 507 wheels and have a wide choice of tires, it means that that bike was well designed to accept the usual ETRTO 507 50mm or wider tires.

The problem with Helix is that Helix doesn't accept (to be confirmed when there will be some Helix delivered) up to 40mm wide tires and that there are very few models available (seems only one remaining).

Yes, I own a Brompton and doesn't like the heavy, cheap Schwalbe Marathon, Marathon Racer, Marathon Plus tires nor the fragile, slow Kojak. What is missing is high performances lightweight folding tires like the Marathon Supreme, Marathon Mondial, Pro-one or Continental Grand Prix.

ETRTO 507 wheels on a folder isn't a unique selling proposition, there are for instance Tern folding with ETRTO 507 wheels.

Now, who would like to have a unique selling proposition that doens't bring any benefit or is a drawback ? And actually, this is exactly what ETRTO 507 wheels is: no benefit, only drawbacks !

For the increase of wheel base of the Brompton, your comments means that you never rode a small wheelbase and a large wheelbase Brompton, if you did, you would know the benefit of the increased wheelbase.