Welcome to the world of flight simulation! I've been in to flight simulation for a long time, and while there are definite rough edges that need to be improved, this really does represent the next leap forward in what's available for this hobby. X-Plane with ortho scenery installed on my system has much longer load times. Prepar3d has lower framerates when you get some good scenery and a good aircraft loaded. I wish flight sim performed like AAA games. But this really does represent a significant improvement to the genre relative to what we've had before. It'll be a while before the high-quality add-on aircraft are ported over and available, as well as other types of content where hand-made airports and such are much better than the mostly-auto-generated content that comes with the game... but out of the box the new MSFS really does look so much more realistic (not just the earth but the sky: weather) and performs better than what we're used to.

So from the perspective of existing simmers, a game that seems to be pretty bad relative to mainstream AAA titles is actually looking really great compared to that status quo.

As for the download system -- yes, there's no excuse for that. I'm not sure how they got that so wrong given the abundance of prior art that does it better. The seeming relationship between Azure load and FPS/stutters is concerning and certainly a new condition that didn't exist in existing sims. Overall I do think the new sim suffers from being released prematurely, as we see so often with software now. But the reason for all the hype and praise is because the flight sim community really is excited about the potential this represents because we've been stuck with such ancient platforms for so long.