The hair trigger is nice too.
I use pretty much everything, the MIDA has benefits.
I think personal preference should always prevail. I could care less what others use (including Thorn). I'm far from a pro, but I like running around shooting crap, and sometimes I use MIDA.
I consider these good reasons to use it.
Im making no comparison to other weapons, or considering "ERMAGERD!! You lost an exotic slot!!!", simply answering "Why use MIDA?".
Sure.
But I'm the worst person to ask. I tend to use "whatever I didn't use yesterday" and that includes Zhalo, SUROS, raid gear, etc. I don't care about k/d or "better". I just play with the perks.