If folding bikes are like recumbent trikes (of which I have a lot of experience), people simply don't realise what they are missing out on until they ride a machine with suspension. As I have described in another thread, when you make actual measurements of ride accelerations, a small wheeled bike with only minimal suspension (like the Brompton) has an abysmal ride quality in objective, quantifiable terms.

On recumbent trikes, I've lost count of the number of people who have suggested that suspension is a waste of time / effort / weight (etc) and then, when they ride a machine with suspension, rapidly change their mind! Of course, there are also some people who have sufficient body strength, innate resistance to vibration (etc) that suspension makes little difference to them. I have found many more of the former than the latter, though.