Okay, I love both Meshuggah and Nightwish. I understand what he's getting at. I disagree with him saying Nightwish isn't metal. It is metal, though they do have some lighter, fluffier songs like "Eva" for example and are on the lighter side of metal. For him to say they aren't doing anything new, well, Nightwish has been around a long time and they were the FIRST true gothic metal band with female vocals, which I think is why he thinks it's not metal. Due to the female singer.
The thing is, Meshuggah probably is one of the heaviest metal bands PERIOD!!!! To compare Nightwish to Meshuggah is absurd in terms of heaviness. Truthfully, it's the same thing if you were to compare Maiden to Meshuggah. By today's standards Maiden is pretty light on the metal spectrum, much like many power bands. (I'm sure I'll get shit for this one) But come on, that's why Meshuggah and other death metal and the like are considered extreme metal.
Overall I agree with his statement though. A lot of bands are pretty much recycling the same material over and over and over again. Truthfully, how many new ideas can there truthfully be left? It's the same thing with any other type of art form. I do wish a lot of bands would put more creativity and ingenuity in their music but at the end of the day, most riffs have already been written.