Because you are assuming thousands if not millions of lights years distances. I am saying there is no need to go that far out - at least until we know more. The information from stars in the local group is less than 50 years old. Since there are 133 stars in the local group, I figure that gives us quite a bit to explore in the immediate (astronomically speaking) neighborhood. And if that is not enough, there are 511 stellar systems within 100 light years, which includes over 100 E-type planets, the data from which is less than a century old.
I have no problem with the idea that light from objects millions of light years away is, to put it lightly, outdated. But I am saying SO WHAT? We don't need to go flying out a million light years or more our first trip. Besides, stellar evolution is measured in billions of years, so even a million light years away is only about 0.01% of the average star's lifetime.
IOW, things don't change as much as your concerns indicate. And, the math was to show that MOST of that space is nothing but big empty. All those movies showing spaceships maneuvering - some not so successfully - amongst a field of spinning asteroids is so much twaddle. The reality of an asteroid belt (even one millions of light years across) is a spaceship could travel from one edge to the opposite edge and never see an asteroid close enough to take a picture without a good telescope. So concerns of hitting something because our FTL ship pops out in a place for which the available data is even several million years out of date are still over stated. What I wrote earlier is NOT an exaggeration. You are more likely to be hit by a meteorite sitting in your living room than run into one in an FTL spacecraft. The same for goes black holes, or the wave front of a supernova, or anything else for that matter.
But that's the point, we just don't know, and even something a short as 7 million light years, is plenty of time for things to move about, even a collision by another astral body would completely rearange the area..
Hell, we don't have a clue what space may look like 7 million light years out, for all we know, it may all be merged into one big ass rock, or infinite amounts of rocks the size of baseballs.
Point is, we just won't know until we send out probes to map the area, that can return to earth so we can travel safely.