I don't typically update anything until I'm confident the update is an improvement. If it ain't broke don't fix it is a good philosophy for a lot of things. Updating is a risk too. I've actually had windows updates do bad things to my computer before.
Windows is the hacker's pincushion, so it's always under attack. I agree that it can be best to wait for verification that an update will be a benefit, but sometimes, it's needed because one of the streaming providers is no longer affiliated with Denon (or the others) or maybe Apple changed their iPhone OS and now, it doesn't play well with others (has happened a few times). In this case, the AVR is the 3dr party device and without the updates, it may not work.
Regardless, something that operates in a network and uses someone else's protocols will need to be updated, at some point. DVD/BD players need updates, routers receive updates, cable boxes receive updates and in some cases, we don't have a choice. Even cars need updates at times and those have nothing to do with their cell/IP systems.
