Thanks!
The idea is that each "secret room" is supposed to teach you about a new gameplay mechanic, that you will be then able to use to solve a puzzle (or open a shortcut) in some other room that you've either already seen or will encounter in the future. The secret rooms are set up in a way that you're almost certainly going to trigger this mechanic once you enter them, so you can then apply the knowledge of that mechanic somewhere else.
For example, once you figured out how the two types of special tiles in "Lucky Eight" work, you can be on the lookout for those elsewhere, because you now know what they can be used for. You may have already found that place or you may need to do more exploring until you encounter it.
I guess this general idea could probably be explained a bit better though. Because it may feel that you're missing something once you find one of those secret rooms, even though you actually already got what you needed from them: i.e. the knowledge of a new mechanic.