Discussion can get heated in forums about topics like this, especially if there are instances of updates causing problems (or in Apple's or Samsung's case, getting caught deliberately throttling performance). There are several things to consider.
First, most of the noise you hear is coming from users who've had issues. The vast majority of people will apply the update and go merrily on their way without so much as a peep. In the case of your phone, there have been millions of devices shipped and it would be devastating to Samsung to have an update that caused serious problems across the whole product line (like the Note 7 battery debacle).
In those vast numbers, everyone is going to have a different configuration, carrier and app list, so while Samsung tries their best to get updates that install smoothly for all customers, it's next to impossible. If you're one of the few who get bit, then that has to be dealt with on an individual basis.
IMHO updates are necessary to fix bugs, plug security holes and give users new features that might not have been available at the time their phone was released. While the feature set might not be important to you, bugs and security should be.
Of course you can chose not to install, but it's still going to nag you about it.
Now, to prevent any problems with updates, it's always best to do the following.
1.) Make sure your important data is backed up before you apply the update. (You should be backing up anyway, right? .... RIGHT??!! ... do it now.
) And turn on Google's backup for your apps and settings (*more about that later)
2.) Fully charge your phone. A full version update can take many minutes (or longer) to complete and will use a good deal of power. Having your phone crap out in the middle of a system update can easily brick it.
3.) Let the update run. These things take time and for version upgrades it's essentially rewriting your system. It's got a lot to do, so let it do it. 30 minutes to an hour is reasonable, but I wouldn't consider it a problem if it took longer ... after 2 hours maybe, but that's going to depend on your phone. An S8 I'd expect to take 15-20 minutes, but if you have low user space or 250 apps installed .... go for coffee ... twice.
4.) When it's complete, clear your caches. One of the biggest problems with updates is that they leave bits of the old OS around, especially in caches that could conflict with new processes and cause lag, battery drain, heat, signal issues, etc. And make sure once you clear the caches that you restart your phone at least twice.
5.) Best practices. Remove all accounts from your phone and then perform a factory reset. Removing accounts disables FRP (factory reset protection) so you won't have any problems with the reset. (Check with Samsung to see if they have a separate reset protection enabled for your device)
Yeah, it's annoying but you can streamline the process if you have a custom launcher that you can backup. Nova or Apex work well. If you have checked the box in Google backup to restore your apps and settings above* it will reinstall everything for you once you've logged in with your Google credentials. Then restore your data and launcher backup and you can be back almost to where you were prior to the update with a clean efficient system.
BTW, the biggest complaint by far for Samsung devices recently is their dropping custom notification tones from the stock messaging app. If that's the worst, then the update can't be all that bad.