Btwin has other, cheaper, bi-fold folding bikes.

You are right, the unique selling proposition of this bike is its smaller folded size, also small folded width obtained by the single side fork. This smaller folded size should make customers accept to pay a higher price.

The short frame and short wheelbase is a consequence of this goal to have a small fold: it reduces the folded length. Note that Btwin doesn't specify the wheelbase (thought, you can deduct it from the overall length and overall wheel diameter)

To make it usable for taller riders, Btwin put a very long seatpost and very high stem.

The bike has also a front block to carry a specific front bag similar to the one of Brompton.

The target customer for this bike is multimodal commuters riding short distances doing the biggest part of their commuting by train, bus, car... Therefore the importance of the small folded size, ease to fold and ease to carry folded advertised by Btwin.

Decathlon, the owner of the Btwin brand, has a lot of shops. I know several people who bought this bike and didn't liked at all. This is the reason why I could test it myself.