"In the end it will also not matter, because when these people reach the distant location, there will be no compatible civilization on earth left."
The point isn't to come back. The point is to go out.
"There is no point in deep space travel as long as we are not able to go faster than light or at least close to light speed."
No point that you understand. There is a point for those of us who would like to seed our planet's life and culture out to the stars. Maybe we'll develop faster than light which will over take those ships, or maybe we won't. But if we don't send out seed ships then we won't have and someday when the rock with our name on it hits Earth we'll be wiped out. This is a very big reason for sending out seed ships.
Personally, I think they should be live ships, not just storage of corpsicles.