I would like to see a nerf as well.
While we are 12/13 M now and most likely be able to kill Archimonde in the next couple of weeks, I do think a nerf would be nice for 2 reasons:
1). At 9 months into HFC and x months with valor most people will be geared fully. This means if you are stuck on something there is no additional gear that will help you and since anyone not already 13/13 M for 6+ months is not a world class player this will likely mean you will be stuck on that boss for the rest of the expansion unless you get a different raid group.
2). After 9 months of no new content players will drop out and replacing them is a pain. A gradual nerf would allow for easier recruitment or even doing more bosses with fewer players on Mythic or less capable players in general.
The above would be bad reasons when the raid is new, but after 9 months of this raid and 6 more to come I don't see the downside of this.