We can't go back today because we don't have a fucking rocket.

If we had the rocket of course we could go back but we don't. Rebuilding the original rocket is very hard or impossible due to how it was contracted and the fact that many of the suppliers don't exist any more and much of the knowledge is lost.

Of course the actual technology we have is sufficient. Rockets are extremely simple when it comes to computers. Most calculations needed for actual burns could be done on paper or a video game nowadays.

We could of course build a new rocket but that is really expensive and the budgets for these things are far lower nowadays compared to the cold war. Still we are actually planning on going there soon-ish.