Yeah, its something relating to a fundamental limitation of the game . . . you know how chainsaws/drills are a single projectile that is "held out" to mine? Versus the picks/hammers/axes that are swung each time, even if autoswing.
I don't know the specifics, but it has something to do with that.
I would guess that when the original drills were implemented in 1.1, it was more for the cool factor of "oh man, upgrade to DRILL!" without thinking of the long term ramifications of what it established. And they were pretty cool, I think.
Hammers/Axes > Hamaxes was just convenience for people, though I've seen significant pushback to get them anyway (some people citing not liking how missing will tear down their trees/walls, etc).