Lack of maintenance is a good reason to use a microcontroller. I can understand not wanting to deal with the complexity of a pi and the associated software updates, but if you just need to read a sensor or toggle a relay and send a few packets you can write arduino code that is effectively set and forget. Most importantly you can be certain its behavior wont unexpectedly change because of some remote update. It's easier now than it ever has been to get started, things have improved alot in just the last 5 years or so.