iLife was very important to Steve, he dedicated a lot of time demoing the apps on stage. He was a huge fan of ripping out all the features of iMovie.

Same with iTunes (which has gotten a ton of criticism over the years), he was the one that kept cramming everything under the sun into it.

I don't know if he was as passionate about X Code, but he sure liked to brag about having the best development environment. Interface Builder in particular seems right out of Steve Jobs' brain (even if it sucks).

Here he is introducing X Code: https://youtu.be/Rh5spZrzu6c?t=59m3s