Whilst on the surface, it doesn't appear that they've done much - Every. Single. Set. Piece. Has. Been. Recreated. From. Scratch. Out. Of. New. Materials. While it looks the same, it's hardly "minor". While you only see the additions - the projection, the screen, etc - what you're not seeing is that EVERYTHING is new.
Would you have considered it 'minor' to completely gut Bermuda Triangle, and replace everything with identical, but new copies of everything?
I haven't seen it with my own eyes, so i'm only going off descriptions from others and the few POVs captured so far, so i'm not judging it until I see it for myself. I feel that some of the criticism seems like it is justified, some of it is enthusiasts being picky, and some is just downright ridiculous for anything but a Disney park.
Sure, its absolutely not ideal that the ride was stripped for so long - but by all accounts this was due to a safety concern. Unless you're in the business of set design and construction, you can't possibly know how long it should take, or why it took so long if it took longer than it should have.
How long did Scooby take to construct when it was first built? How much of that was actual track build, and how much was theming? We've seen coasters go up super quick - and in the soundstage, weather isn't a factor - so the actual build time would be quite short, yet, as I recall - construction took a fair while...