"no-one dying" is not a good metric to justify a dps pulling extra mobs being OK.

If no-one dies, it's because the healer's working overtime healing you, which also then means the tanks has to run round collecting the mobs that are now on the healer. More time both of them are having to do this, the less time they are both dpsing the mobs. in lvling dungeons, clericed healer can easily top the dps

tl:dr you "speeding up" the run in this way isn't speeding it up at all, its almost certainly slower, and also forcing them to work harder just to keep you off the ground.