First off I didn’t listen to the review … just giving an option on why bad speaker reviews are often given.
Everyone has their own expectations and tastes. If used to a bass heavy speaker which accentuates the boom in your music a flatter response may sound/fall … well … flat to you. I think this is especially true for headphone. Also it depends on what you drive it with … if you like it loud and drive it with a low wattage amp you’ll get distortion … Next up is how some speakers lack detail … a good speaker can show flaws in your music that your old ones didn’t. I’m sure other can come up with more reasons …
To sum it up … the speaker is often the first thing blamed when the resulting sound does not meet expectations.
