I recently realized that I dread key changes in the music I listen to, and most surprising was the realization that I view it as a barren musical device: it frequently suggests a lack of inspiration. Most of the time it feels like the composer simply reached the end of the bridge and decided "I'm going for it".
That's not a reason, ever , to switch keys on me. Some people are going to eat that up, but I won't let that garbage fly past me without noting its formulaic application...and judging the composer for it.
These revelations struck me quite hard while listening to Miho Fukuhara's "Starlight". At 2:40 I cringed, just waiting for her to usher in a pedestrian key change. Imagine my surprise when she didn't!
So be sure you don't try to impress me by switching keys at the end of the bridge.