There are some MMO type quests, sure but they exist to let you explore

You can drive exploration without smothering the player with fetchquests, see: The Hissing Wastes

the great landscape they set out in front of you

I couldn't enjoy the landscape of Niagara Falls if my 6 yo cousin was constantly yelling about TMNT in his nasally voice. In the same way, there is no time or space for any sort of immersion of the landscape in DA:I because it constantly suffocates you with garbage content.

If you don't enjoy the filler you don't necessarily even need to do it

This would be a valid argument if the filler wasn't the majority of the side content in the game. I recently counted the number of filler sidequests- defined as any quests that is only there for padding, and that has minimal narrative, trivial rewards, minimal dialogue and no choices present. You don't have to strictly agree with that definition, however I think it's a fair one. DA:I has in total, 120 fetchquests. Every area has either (1) the majority of its side-content being filler or (2) at least half of it being filler.

By saying "you don't have to do it", you're suggesting to skip the majority of the game. Now the criticism moves to "this content is garbage" to "this content was so garbage that the only way to enjoy the game is if you avoid the majority of it"

Also, "you don't have to do it" does not make the filler any less bad.

Games are allowed to have content that not everyone really cares about

Absolutely, but not when that content makes a big chunk of the game.

There are a ton of games with collectibles and explorer quests like the Riddler Trophys in Batman though those aren't necessarily for everyone

Outside of shitty filler quests, DA:I also has collectibles. Riddler trophies are also a lot better than shards, bottles, or mosaics.

. The base game, characters and story are incredibly engrossing

That's debatable, the story is quite average and a contrived at certain points, the main villain is a joke, and the combat is a really flatlined experience. Characters aren't the peak of writing but they're better than the usual stuff you get from AAA games today.

DA:I is just an average game. The only thing it has objectively going for it is the GFX and the VA, and neither can bring DA:I up from its mediocrity.