I usually don't argue with people regarding their taste in music, as it's a highly subjective matter, but to put "Opeth" and "lazy, generic songwriting" in the same sentence is laughable.
Orchid - Morningrise era : The antithesis of lazy songwriting. Both albums were written entirely in counterpoint. That means, two or more entirely different lead guitar melodies playing simultaneously throughout the entire fucking album, in a way that combined result of this polyphony sounds better than each melody played alone. Do you realize how hard it is to write an album like Orchid or Morningrise ?
My Arms Your Hearse - Still Life era :
http://www.youtube.com/watch?v=yrBrH5PZtcc
"lazy songwriting" my ass !
Blackwater Park - Deliverance era : Progressive/psychedelic rock influences while maintaining an death metal edge, and they pulled it off masterfully. If anything, the fusing space rock with death metal is adventurous, rather than "lazy" and "generic".
Damnation : Amazing soft rock effort. "Generic" applies here, but certainly not lazy.
Ghost Reveries - Watershed : Although I like both albums, but I'd say that calling them "lazy and generic" is arguable here, but definitely does not apply to Opeth as a whole.
Regards