Please ignore relativistic effects and the effects of the expansion of space-time due to the expanding universe theory for the purposes of this question.
Whenever someone asks what is the speed of X, we always ask "with respect to what"? We can calculate the speed of something only with respect to another object. A train's speed is calculated relative to the ground. A spacecraft's relative to the earth/sun and so on. It seems fair enough.
I understand there is no universal frame of reference. Because, well, there is no sense of direction in space, except relative to some other heavenly body.
Agreed there is no universal frame of reference. But I think that actually implies that there is no universal origin in the universe. Certainly not that there isn't a universally acceptable notion of distance.
1 meter is 1 meter, no matter where you are. If I am covering 10 meters every second, my speed is that much.
It is only that we dont feel the speed with which the earth rotates, since we are on it. When we say a car moves at 60 kmph, that is with respect to the earth, but in reality, if we were to measure it with respect to space, our actual speed would be earth's speed in space (+ sun's speed in milky way etc ) + 60.
Other bodies only give us a reference point to feel speed. They shouldn't dictate how we measure it.
The gist - Isn't it incorrect to measure our speed with respect to another body (say earth), just because we can't feel/visualise our speed in empty space, which should be the actual speed of any body.