Maybe it's a marketing move to fit the disc brakes, as they do look nice?
I think that is part of the reason, and why I would suggest the 5.0 bike will do well in Japan etc (they have a greater range of deluxe/optimally specced folders over there), but probably not so well in Europe and the US. I always liked the pared down simplicity of the Strida - less things to go wrong (although some of the components seem a bit fragile).Discs apart, the rest of the improvements seem worthwhile.
Or do you mean something else perhaps, maybe range of adjustment?
Precisely, the taller you are the higher you need to raise the seat, and in so doing this brings the saddle closer to the bars. This is unfortunately the opposite of what most taller riders need. I found the position (at 6' 2") uncomfortable.
We use our Stridas when we're travelling & are unsure how far we'll ride before we set off, depending on how interesting the area is where we've parked or landed, & have done quite a few trips of 12 to 15 miles just fine. So I'm not clear as to why you think they're only suitable for 2 - 3 miles?
I didn't say the Strida was only suitable for 2-3 mile rides, but I would contend that is what the bike does best - particularly in concert with trains/buses/cars. I am sure longer rides are possible (I have only had a test ride on an older model), but there are many other folding bikes I would rather ride 15 miles on. I have no doubt someone will suggest that it is possible to do the Paris-Roubaix on a Strida, but that doesn't mean it is the best tool for the job.
We've had punctures on a few of those longer trips though :-( I'm trying to find a UK supplier for "Mr. Tuffy" liners which riders from the US say are quite good.
I have used the Panaracer Flataway Liner which is similar and likewise effective. Easy to get hold of in the UK. Try Wiggle.