For me, my current interest in mechanicals is entirely because the output is limited only by the battery. No "amp limit" of the VV circuitry or anything, which makes for an AMAZING vape on an RBA. With a mechanical mod, you can wrap a 1 ohm coil and it'll fire no problem. In the RBA scene and particularly with stainless wicks, even 15w sometimes isn't enough to produce a great vape. It also allows you to use thicker coil wire too, it uses more power and shortens battery life but will last 10x longer.
I don't really care too much about the "fully mechanical" simplicity aspect of it actually - my VV stuff has been dead nuts reliable from day one and I've never had an issue.
It's odd, because when I started vaping all I wanted was an awesome mechanical mod. Then VV stuff came out and I thought I'd never go back there again, eff being tied to battery voltage. But here I am again, lusting over mechanical mods again.. They really are the dinosaur of the vaping world though. It's funny though, now I can finally appreciate the awesomeness of stuff like the GG's.