A key goal of these missions has been to understand the composition and structure of asteroids, which happens to also be pretty important for how they might be

A key goal of these missions has been to understand the composition and structure of asteroids, which happens to also be pretty important for how they might be defended against. If they're a loosely bound pile of dust, then it might be better to dig in and blow them apart into smaller pieces to mostly burn up, but if they're more solid, redirection would probably be the only viable solution.