Oliverbellringer:
I'm not sure if this was done deliberately by Nelvana as a way of making the stories more engaging
Almost certainly so - that, and simply having to make different stories of different levels of complexity run to a standard length to fill the time-slots for the show.
The series was designed to allow the stories to be shown or viewed in any order as much as possible - so there are few if any big introductions of characters, and instead Tintin encounters recurring characters as if he has always known them, and they him. This allows viewers to engage with the series, whatever story they start watching with, and TV stations could put the series on endless rotation, or show individual stories as filler material, and not have to worry about a reference to a past adventure confusing a new viewer.
This also means that if you can get a new viewer to watch one story, they might want to see more, so something like the scene in the tomb is a good way to entice those watching to see more.
Oliverbellringer:
I've always wondered if Studios Hergé (or their successors) were ever consulted when it came to making them?
I'm sure they were - they are the source of the material, after all; however it's not to say that they will necessarily have been overly controlling. For example we know that when the Young Vic theatre company mounted their stage show
The Adventures of Tintin, they were given a pretty free hand to adapt the material as they saw fit, and so we got a Snowy who peed on the audience and fart jokes in the tents on the mountain, and the Studios didn't intervene.