The words of caution are sound but it doesnt have to be that way. I use my aircraft for business a lot. Journeys of three hours by car typically take 30 minutes by aircraft. However taking into account the journey to and from the airport and preflight its around half the time saved. Further afield or to places like the i of W and the time saved increases dramatically. I can comfortably do manchester and back from the se or cornwall and back in a day - not somethimg i would want to do by car. With time the flying is a lot less stressful than driving - you actually arrive a great deal more relaxed.
It is true despatch rates are lower so you cant build total certainty into your planning but again with experience the despatch rates can become surprisingly high.
The downside is it takes time and committment to get to a point you are comfortable with longer trips without spending hours planning, worring about the weather etc. You can get to the point where you can plan any trip within 15 minutes. A reliable and quick aircraft helps as well.
However i agree realistically we imagine with a newly minted ppl all this becomes possible - sadly it doesnt. However trips like the one you propose are more than possible on an occasional basis, are good fun and exactly what private flying should and can encompass.