Few reasons bro...
I find I am not using the 35/1.8 a lot. FOV is 52mm like a normal lens, but I prefer something wider. When you look at wide angle pictures, you get a sense of dynamic movement, this is due to perspective, since the longer the focal length, the more compressed things look. The shorter the focal length, the more exaggerated distances look. So that wider lens will give you more sense of "movement" due to that exaggeration in perspective. Especially when you go in close to your subject. I like this effect wide angle lenses give you.
24mm on APS-C is around a 35mm FOV. This is a good FOV to have. 1) subjects still do not get too distorted (wide end of 'normal'), 2) it is slightly wider than your 50mm FOV.
Another reason is that this 24mm lens is a FF lens, so if I move to FX, I will be able to use this as a true wide angle prime.
Lastly, baby is coming, cannot anyhow anger wife. If I sell a lens, I can easily justify the purchase of another (even though the new one is more than twice the price of the old one).
So far if you ask me now about some feedback on my new 24mm, I can tell you I am very very happy. My shooting style has also evolved with this lens, capturing more dynamic photos, getting closer to my subjects.. I am very very satisfied...
Couple more pics... I really love this lens!