It is, but I'm not sure I'd count that as a positive, due to the main reason that it has ended up as large as it is.
GW2 has a similar appearance collection log...
The main reason WoW's is the size that it is? Recolors. While the game has had a significant amount of time (almost 15 years at this point) to add armor designs and types for each armor type, there is a significant amount of asset reuse outside of the more individualized tier sets...and each variation in color is considered a different piece of gear (which also results in less overall appearance options - we have 105 different dye options to recolor our gear that can be dyed - the average recolor in WoW gets maybe 4 variants, with occasionally more - and GW2 has even more - 382, last I heard - with the added bonus of permanently unlocking the dye for use once you obtain it once).
Each individual recolor of a piece of gear gets its own "spot" in the log, and there have been a lot of recolors over the years in that game. Whereas GW2 just has to show and track the base color instead of every recolor option, and then recolors are handled by the player through the dye system - what takes up 5 or 6 or 7 slots in an appearance log for WoW only takes up the 1 in GW2. It's an estimate, but I'd hazard a guess the log would be a good 50% to 60% of its current size if it didn't also display all of the recolors of items.
Again, I'll take how GW2 handles it over how WoW handles it, including the appearance log. The one area where I think they fail compared to either XIV or WoW is in the acquisition of the item needed to apply appearances to gear - the transmutation charges primarily come from either timegated chests from their WvWvW, or from chests that are primarily opened via keys obtained from the MTX store, or directly from the MTX store...and while you can use gold to get those gems, you're now back to talking about a more expensive process in terms of in-game currency.
Take everything about how GW2's version works, combine it with the cost of glamour prisms as they currently stand in-game (they are super cheap to obtain) here, and I think you've got a good system. If there's one thing from WoW that would be nice to have its the ability to view all the sets as sets in the appearance log, but everything else I'd take from either this game or GW2.