Revenue from video games follows a time-series decay curve that peters out to basically nothing after a while. Blockland is fortunate in that it had a massive second wind after being re-released on Steam. And as far as I know, people are still buying the game even though it's been fifteen or so years.
The problem is that developing Blockland has no return on investment anymore. Unless Badspot makes some herculean effort to completely remake the game, any additional updates aren't going to translate into additional units sold. He'd be working for free, and nobody works for free.