Providing you have sufficient power for the desired SPL, there's no advantage I can think of with a more powerful amplifier. Some people will mention the benefits of headroom. Unused headroom is...well, unused, right? And if you did not need the power, it's unused.
Also note that it's pretty easy to be in a situation where more power is like using an eye dropper to add water to the Pacific ocean. When you get up to 100 watts of power, you need 200 watts for a noticeable improvement.
Back in the old days, theaters used massive horns which were really efficient. They needed very little amp power, which was good, because I am not sure high power amps were common "back then." Seen one of those horns at the broadcasting museum in St. Louis Park. Heard it too, pretty cool. So if you have efficient speakers, you don't need 100 watts IMO.
With most speakers though, 100 watts is pretty good for home music and movies if you are not trying to hit "reference level" SPL. If you are, you are going to have to spend some pretty good money.
Another answer is buy all you can afford, and don't look back
That's kind of what I did, I have 2 external amps plus my Yamaha Z7. But it's a bit of overkill. I noticed that lower end receivers run out of power. But don't have the power supplies you see with Outlaw, Emotiva, etc. I would spend the $1500 or so, next time I bought an AVR, to ensure the power supply was good, and maybe sell the amps - they are not needed.
I think people worry about power too much. 100 honest watts is a LOT of power IMO.