No big reason other than a) novelty b) reliability and a certain amount of set and forget and c) they're in stock and surprisingly are a comparable price to BB7 or TRPs. I think if I was building this up more as a travel/rinko style bike I'd go with mechanical to avoid the undue hassle.
Cheers. I've only ever run mechanical discs so these details are important. Magura also use mineral oil I believe.