Here, I put this in a DnD Beyond thread similar to this one (may have been created by the same person), but I think it is a good explanation to what Wildemount has over other settings, namely Forgotten Realms.
"Okay, I'm not a Critter, but I have seen Critical Role a few times, enjoyed it, and know a lot of info about it from the Critical Role Wiki, because I just don't have the time to watch the show. I also have Explorer's Guide to Wildemount and have read nearly all of it.
So, what is the main thing IMO that makes Wildemount better than Forgotten Realms? Here it is:
It's newer.
Now, let me explain. Just because it's newer doesn't automatically make it a better setting, because the fact that Ravnica came to 5e less than 2 years ago didn't make it the best campaign when it came out. No, that isn't what makes a campaign setting good, but it is a huge advantage.
So, what makes it better is that it has less expected of it. When a new Forgotten Realms book comes out, there's more to be expected of it. The Forgotten Realms has been around for a long time. Since near the beginning of D&D. It has a ton of lore. I recommend you go to the Forgotten Realms wiki and just look up the amount of things described. The future has been described. They have rules for outer space and all the comets, planets, and moons in the crystal sphere. They have names for thousands of characters. They have a chronology that keeps track of thousands of years, detailing everything that happened in each year.
Wildemount isn't like that. It's not super filled with lore. In my opinion, it has a great balance between lore and lack thereof. It leaves enough things open and a mystery to encourage others to fill it in with their own information. (That's why Eberron is so popular.) If you want to know something about the Forgotten Realms, you just search the wiki, or ask Ed Greenwood or Chris Perkins online. That's not how things work for Wildemount. You can search the wiki, but it has less information on the world than the book does. There's a bit of info that exists only on the wiki, but not much. Anything else, you make up. Matthew Mercer has encouraged people to make Exandria their own.
There are many things that Wildemount has that are better than the Forgotten Realms, but the main one is the lack of lore. It seems backwards, but it's true. There's simply too much on the Forgotten Realms to draw many people to it. Exandria doesn't have this problem. Greyhawk has this problem, so does Krynn, so does Ravnica and Theros, and so does Eberron to an extent. (Eberron is different. You're highly encouraged to make Eberron your own, but there is a lot of lore to take in from all the books on Eberron.)
Wildemount has many things that draw people to the setting. Critical Role has the biggest impact on this. Tons of people watch the show, which makes it a very popular setting. There's a simplicity to it that makes it also drawing. Additionally, the lore of the world is very good. The conflict between the typically evil races and the typically okay humans in the war between the Kryn Dynasty and Dwendalian Empire is very drawing. People play Eberron to deal with the fallout of a large war in an unexplored world. People play in the Forgotten Realms to get into the lore and grand adventures with world shaking events. People play in Krynn because they loved the stories in the Dragonlance books.
People play in Wildemount for the fresh new setting. It's largely unknown. This is good. People like new things.
This is why I think Wildemount is drawing. I might be wrong, but this is what I've observed.
I hope this helps!"
Quite a long post, but I think it makes sense that the main draw is less lore.