Personally I thought it was the perfect system, I have no qualms with boss battles and certain NM's being instanced. Places like Seasearpent grotto were great (Although they lacked a instanced area at the end) the BCNM areas are perfect as well going through the beastmen fort to fight the beastmen forces at the end (Instanced) even if the BCNM is a far higher level than the area it's placed it gives the developers a area to develope the content around.