Not to be a dick or anything but learn to use your aggro drop, you are going to need it when you have 7K HPS at end-game. I can't remember the last time I, on DD or healer, didnt use my aggro drop on pretty much every CD during group content.
As NoFishing commented, 7K HPS is not the same as 7K HPS effective
. Overheals don't count towards threat.
Go look at the torparse statistics for healers. Pick any ops-level fight. The top players in a heal-intensive fight do closer to 4k effective
It's not that using your threat drop is a bad idea, it's just that failing
to use one's threat drop is not the reason mobs come after you ...