If your DPS is halfway good, your aggro won't drop below the one of a BLM spamming blizzard, even with aggro decreasing skills.
And, aggro might be a bad indicator for DPS, but it is one. Don't tell me you won't get worried if you meet a BLM being #5 downwards in the aggro table, no matter if they use Quelling or not
About the rest of your post, I totally agree.