As far as i know, Badspot aims for a wide public, thus also aiming for the older computers.
The new Torque engine is awesome and all, but requires a better computer then some still have.
Both the new and older computers can play Blockland now, but when he switches to the new engine, i guess the older can't, thus he will lose some of his public.
And indeed what has been stated before, switching from engine requires a lot of work.
I would also like to see this happening, but you never know what he's up to. ;)
(Correct me if i am wrong with one of the above statements)