Colour definitely can improve the experience, especially in newer comics from new artists, or even older experience professional artists. There are some manga that have been going 10years or more and without colour (or sometimes even the coloured panels/front covers) if characters look too similar especially when they're also in similar plot positions I can spend five minutes or more looking at them going "but which smug jerk is that?" so sometimes colour can really help. I enjoy the experience a lot more if I can just look at a character and recognise them straight away, which is why you also see the each character has 1 outfit trope, of course.
And greyscale or B&W or any limited colour pallet is hard. It takes a lot of work to look good and can be really easy to mess up. I know lots of people seem to act like colour comics take longer and are harder (and that's an entire debate on it's own) but it can also absolutely be used a crutch as well.
And the wrong colour scheme can be really jarring too (although that can be on purpose), If you don't know what you're doing colour wise a neon colour pallet doesn't really work with horror and dull colours won't work with sparkly romance (in most cases) if you're not sure forgoing colour can help there too and make it better for the reader.