I can see your point in some ways regarding old scenarios but I try to look at scenarios as books. By this I mean that there are scenarios that are very good and have aged well with time to become classics. Like books on your favorite books shelf in your office or library where you like to re-read them on occasion or recommend to a friend.So if you're looking to help a newbie learn the game, and looking for
something else than tired old re-runs of Gavin Take, Totsugeki
or Puma Prowls, try out "Mala Zemlya", "No Step Back", "Storm
Over Mariupol" or "Surgis l'Enfer" instead.
I don't think even the most jaded veteran could help but try them out
with his new opponent. And you can even up the degree of complexity
to suit the experienced players.
These old scenarios are still fun and there are many articles written about them which further helps you learn the game. It can then be a goal to learn the game from these old (text book) scenarios and then move on to the new stuff and believe me, there are more scenarios out there now then you can ever play in your life time. IMHO
Either way, as long as your playing ASL and enjoying it then nothing else matters.