Maybe it's just me, but I always loved Nemesis systems. One of the most memorable parts of the REmake 2 was being chased by Mr X. The EMMIs are in the same vain for me. They're like a better SA-X, which is another nemesis in Metroid that is one of the most fondly remembered parts of Fusion. My one gripe with them is that I wish each had a bit more variety. Otherwise, it's a fun cat and mouse game to play with them.

Just wait until speedrunners discover how to break their tracking behaviour and start styling on them.