His goal wasn’t to create an art project though, but to create an actual instrument he can use. The artistry stuff and making it look cool was what made MMX a failure. I agree that the MMX videos were still fantastic content, but that thing was doomed.
Tightness: it’s a compound effect of every part, so afaik he’s just trying to make sure each part is as precise as possible, and selecting the most precise / consistent design out of the available choices.