Exactly. The definition of the meter was originally derived from the circumference of the Earth and the second is (now) defined as a specific number of vibrations of a particular state of a particular atom. If you want to change the meter to make the speed of light in vacuum a nice round number then you'll end up affecting pretty much all of the derived units upsetting the whole SI system.
And in the end it doesn't matter. You should just use the right number, which is arbitrary and landed on 7500 m/second and change short of being 'perfect' but it would have been an incredible coincidence if it did.
The reason that didn't happen is because the speed of light was one of the harder numbers to pin down and the first estimates and later refinements happened much later than the definition of the meter. And to complete the circle: the meter is now defined as a fraction of the speed of light! This has the interesting property that even though we may get better measurements for various constants the fixed ratio means that SI as a whole remains standing.