What all does this erase? Is it safe? Why wouldn't this be built in to Android to happen automatically after an update if its recommended? Suspicious of BS here...
Also wanted to note after a few days, my battery life is still not as good as it was 3 weeks ago when I bought the phone.
Ask with a better attitude next time and I'm sure more people will answer and help you.
No BS, it's safe to do it, not a single personal file or app are deleted just OS junk. Why it doesn't do it automatically? Well, ask Google, and even if they does it now (no way on knowing) no harm on doing it again, as most of the time your phone begin to behave strange or not normal, a simple Wipe Cache Partition can do magic.
It's fine if you don't do it, that's up to you, but a thing like this that can take no more than 5 minutes in total to complete, can save you tons of time troubleshooting and also a lot of frustration.