Because my Fuji kit weighs less than half my Canon kit (and I've already got the lightest Canon FF DSLR) and performs just as well in good light. Being a "hipster" has literally nothing to do with it. If Canon came out with an EOS M with the same capability as the Fuji system (lenses, settings, EVF, the list goes on) then I'd go with it if it supported the same EF to EF-M adapter support as the current M.
Fuji has a lens for almost any need I can think of and all of them are top performers at very reasonable prices for what they offer. The bodies are catching up quickly to DSLR's (though not quite there yet for some needs) and did I mention they're significantly lighter and smaller? I don't like lugging my DSLR with me everywhere I go, it gets in the way far easier than a mirrorless camera does.
Plus you get the added bonus of being able to use literally any lens ever on it. Using my BavEyes focal reducer I can use my FF lenses in pretty much their full glory, same DOF, same FOV (almost, off by a few mm) and on an awesome AA-less sensor with amazing color rendition (seriously, Fuji's colors are simply better).
I'm not ready to abandon my 6D yet because I still need the low light capability and I have a preference toward an OVF (could be unjust given how much better the X-T1 EVF is said to be) and the DSLR still gives me more room to grow if I need good, fast and reliable AF later down the road (right now I don't).