Number one reason, even with Spotify Premium, their so called "high quality" streaming is still a very low bitrate mp3, one of the worst online in fact. I got to talking to the guys over at Audio Adviser the other day and they recommended Tidal if I wanted true high definition streaming, so, I looked into it and WOW, Tidal has true hi-res, MASTER AUDIO, lossless streaming at 96kHz/24bit, and not only that, the monthly rate for the Hifi subscription, which you need to have to get the Hifi and/or the Master Audio streaming, it's $20 a month BUT, they have a MILITARY DISCOUNT of HALF. That $20 a month is now only $10 a month, which is what I was paying for Spotify without true hi-res streaming.
I am VERY glad I switched. The difference in sound on the theater is a huge improvement, so... TIDAL... if you want the best high resolution streaming music on the internet, and if you're military or a veteran, get the discount.