One of the reasons that I purchased the N5 is that I knew I would be towards the front of the line for OTA updates. I had already moved to ART and the Kindle will too in the near future I suspect. Most updates seem to improve the UI, speed up the device and use less power doing it. Moreover (particularly with Lollipop) the switchover from G4 to WIFI and even different AP's has become almost seemless.
If you want to install a mod then you have no choice. However, those who want their Kindle to remain, well ... a Kindle, might want to think about the trade-off. Personally, I don't need root enough to roll back several iterations of Android.
Your mileage may vary.