Yes, but I'd argue it's also easier to create something cool when the theme is as narrow as "vulpera monk" or "dark iron shaman." That's
very specific and easy to hone in on compared to "Uldir plate" or "Nazjatar cloth."
I think one of the issues with doing sets based on armor type rather than class is that the theme has to become more broad. The tradeoff is you get to do more themes overall, at least ideally. The later content seasons in BFA didn't maintain the unique Warfront/PVP sets that made the tradeoff actually worth it in Seasons 1 and 2. Of course, there's also heritage armor in the mix...
I mean, we can calculate pretty easily the total number of new armor sets added in both expansions:
Legion:
- Demon Hunter Starter + Order Sets x 3
- Quest 1 x 4 Armor Types
- Quest 2 x 4 Armor Types
- Dungeon 1 x 4 Armor Types
- Gladiator x 4 Armor Types
- Season 1 x 12 Classes
- Season 2 x 12 Classes
- Dungeon 2 x 4 Armor Types
- Season 3 x 12 Classes
- Dungeon 3 x 4 Armor Types
- Rare Argus Sets x 2 Armor Types
Battle for Azeroth:
- Horde Quest x 4 Armor Types
- Alliance Quest x 4 Armor Types
- Horde Dungeon x 4 Armor Types
- Alliance Dungeon x 4 Armor Types
- Raid Season 1 x 4 Armor Types
- Horde Season 1 x 4 Armor Types
- Alliance Season 1 x 4 Armor Types
- Raid Season 2 x 4 Armor Types
- Horde Season 2 x 4 Armor Types
- Alliance Season 2 x 4 Armor Types
- Brawler's Guild Set x 1
- Season 3 x 4 Armor Types
- Season 4 x 4 Armor Types
- Heritage Armor x 10 Allied Races
- Heritage Armor x 6 Core Races
Unless I miscounted, BFA has introduced about 65 new sets, while
Legion introduced... 65 new sets.
Now, that's not including recolors of old gear like the Order Hall gear in
Legion (except for Demon Hunters, which was new) or the Island Expedition gear in BFA. I also grouped pre-purchase gear (DH for
Legion, Heritage Armor for BFA, Eternal Traveler for
Shadowlands) with their respective expansions.
I'm pretty sure I didn't miss anything, so the two expansions are actually pretty damn comparable when you look at the whole picture.
Edit: I forgot that there were only rare drop Argus sets for plate and cloth. So actually they both seem to have exactly 65
new armor sets, unless I missed some.