If you can skip bosses you should, if you know you need something from that boss then say that to your group if they are skipping it and they will naturally kill it, if not, just pull and they have to kill it
I just ran into a group. told them many times and they refused to attack bosses they could skip, they only wanted the comms and be over with it.
Many bosses has random set item. It is very hard to specify if that will drop so it is better to kill boss and find out.