It gave your horse extra health actually, so not purely cosmetic. But I think in a single player game that also has extremely good modding tools, it doesn’t really matter. If you want to pay to win your single player game, you do you.
Horse armour was mostly a landmark for showing companies that consumers were willing to pay for micro stuff like that. The potential return vs effort invested was crazy. Todd himself said that they try doing nice DLC that gives you good value for your money, but it’s hard to justify business-wise when the horse armour is so cheap to make and sells so well.
GOG is getting a nice little pr moment off of this but you’re getting basically the same license, no matter where you buy the game.
The root of evil in digital distribution is the DMCA anti circumvention clause: it is illegal to circumvent a DRM protection to gain access to some copyrighted work, even if you in actuality possess a license to the work. This law gives big platforms far too much power to control how you interact with their products.
It should be legal to modify a work to allow it to be played offline, to make copies for archival purposes, to fix the work to run on newer platforms, etc. As long as you have a license to the work you should be allowed to take steps to ensure your rightful access to it.
By the way, the root beyond roots of evil in digital distribution is the insane length of copyrights themselves. Why are patents 20 years, but copyright extends to 120+? The answer is pure greed.