Is lukewarm on the Forgotten Realms
Even though I absolutely love 5E, I have to agree. But, this isn't just the case with subclasses and the character creation system. In 5 years of 5E, we've seen one book with rules for "alternate campaigns", apart from the DMG, and that book is GoS. As for subsystems, XGtE is fine, I suppose. But, the amount of crunch that has been added to the game is actually pitiful when yuou step back from the game.Yes, this is what I mean by breadth based design, not depth based.
Basically, you can have many characters, but you can't have complex characters.
5E isn't crunchy enough for many of us.
Most subclasses just rehash the same bonuses anyway, just handing them out in different combinations: such as getting advantage to one skill or special case. There has been little to no real invention when it comes to new mechanisms.
Basically, the success of 5E has meant WotC is treading water. They aren't going to add substantial new content for fear of disrupting their cash cow.
I own a lot of 5E books, and I've read more. Really, if you consider what the "splatbooks" actually contain, WotC's hesitation has been somewhat ridiculous.
VGtM is a wonderful splatbook, that gave us no new systems. Even the (awesome) races included are just more of the same, leading to greater depth of options, but less breadth of options. Also, Yuan-Ti Purebloods were not adequately playtested and you can't convince me otherwise.
TFtYP was an adventure book, 'nuff said.
XGtE contained new subclasses, and a few new new options for DMs, although most of these were very minor. DMs were given new rules for tool proficiencies, a new encounter calculation method, and a few very bare bones subsystems, along with what amounts to a few paragraphs of errata. I still love XGtE, but there was little in the way of new systems of consequence here.
MToF contained new races and new monsters, with no expanded options for players (i.e., they have new races, but not a greater breadth of class options).
GoS was an adventure book that gave DMs a good and solid ruleset for sea exploration.
What does this show?
It shows that WotC is consistently releasing great products, including ones that are good (XGtE) and amazing (GoS) for DMs. The problem is that, in all of those years, players have only received subclasses and races, oh, and backgrounds I guess (but, backgrounds? Really?). The recent Alchemist class is the first new class to come out in 5 years. That's a long time!
Furthermore, if each splatbook contains nothing more than new race/new subclass/new monster, this formula will quickly become routine. What's the point of buying what amounts to a Monster Manual 3 is you know that all you're getting is more of the same.
Perhaps I'm exaggerating the issue, but my concern is that WotC will not cater at all to a want for newer systems. Now, is this a purely selfish desire? Well, I hope not, as I've tried to justify it, and I think it's fairly rational.
What I am sure of is that WotC's content release pace is far too slow.