Did many people complain? Only two that I know of, and it just so happens they have a Youtube channel, so you better believe Playtonic changed that challenge. Other reviews may have referenced it, but I didn't listen to any of them: I knew I could trust Gamexplain, so they're the only ones I watched with the firestorm of reviews back then.
Look, I sincerely believe the Grotto needed change. But fair changes: ones that made the lighting effect actually useful (before, you literally couldn't tell when you were right in front of an abyss), and maybe took away a few of the unfair elements like the large corplet boss or the bees. Personally, I would have been fine with just making the darn glow element better.
What they've done to the place now? I agree, it is a travesty. It went from a challenge to a walk-through. There are more challenging obstacles in line at Disneyland! (OK, that is hyperbole...)
Even Gamexplain didn't want them to change THAT much. In their video, they say "change this, or this, or this." The key word here is 'or.' I think it was a knee-jerk reaction by Platonic. Just be grateful (or spiteful, whichever) that Rusty Bucket Bay is safe from changes like this.
P.S. Black-Hole-In-One was given some pretty dumb changes as well. What exactly is supposed to be the challenge behind that one now? Walking? At least the Grotto is still dark...