1. There is an unwritten rule that only tanks pull. I know because, as a tank, parties have always waited for me to pull, even if I just stand there for 5 minutes. That's proof that the community, in general, sees waiting for the tank as an unwritten rule.
  2. Your concern that a lot of new gunbreakers won't do big pulls doesn't matter, because a lot of tanks already don't do big pulls, which makes me tank more often than I otherwise would. I tried queueing for experts on DPS jobs sometimes and they were pulling 3 enemies at a time and I was so bored. That's why it's just the truth that if you want big pulls, level a tank or have a tank buddy that you do content with.
  3. If you pull when you're not the tank, a lot of tanks will refuse to grab aggro of it. Why? Because they didn't pull it and feel that is stepping on their toes or insulting them. If you're going to pull without the tank, be prepared for salt and be prepared to tank it yourself on a healer or DPS job, which is possible depending on your item level and mob actions. Almost every tank I've ever discussed this with has said they would not pickup enemies if they didn't pull them, so keep this in mind if you do it.
  4. Sometimes I won't pull a few extra mobs in a big pull if I feel that most parties or that party in particular can't handle it, or if my tank cooldowns won't stretch far enough. I personally just take aggro if someone pulls those extra mobs though. If they pulled them then they are prepared to heal them or DPS them fast. If we wipe, which we sometimes do because my original judgement to not pull was good, then they know it's on them.