Looks are a big part of it I'll admit. I love seeing those belts and pulleys spin around. Call me sick I don't know what it is.
The other reasons are quieter running. A chain stretches over time and gets noisy.
And it is a lot easier for cam timing adjustments and dial in. Obvoiusly you don't do this often but its very handy during a dyno session. The ultimate idea is to have an adjustable pulley
to get fine timing adjustments so you can get it 100% spot on.
I don't think it will be a pain either if my initial thoughts and comparions come off as what I am hoping is the crank pulley will slide straight on. The cam pulley will be no real problem
as at worst the outer can be welded to inner of the chain cog. I have a spare you see. You are right that the gains might not support a lot of work and cost so it will only go ahead if it
is mostly a bolt on affair.
The mini conversion is a piece of cake as they make a new backing plate that has the required oil seals to seal against the inner surface of the new pulleys and bingo that's it it bolts
straight on in place.