"Why did people like this in 2001 & it got such good Metacritic reciews?"
At the time, I only had Nintendo systems & missed Symphony of the Night. So I went from the NES/SNES Castlevania games straight to a Metroidvania. It also had been 7 years since the last major Metroid-style game on a Nintendo system. So Circle of the Moon was amazingly impressive.
I think your criticisms in retrospect make sense. But at the time, we had very little to compare it to.