I've been informed that you only receive dilithium from exploration missions that you complete "on level". If instances are all level banded, why then is this restriction in place? Is this intentional or an oversight?

Either way it doesn't make much sense.

lemme just add that there are many reasons why someone wants to explore a certain sectore over the other (Accolades, types of anomanomnoms ...)

Currently VA's have two explo dailies, just let us pick which once we want to do....

Agreed, unless you add in dilithium awards for every mission in the game, with level scaling, every explore should earn you dilithium.
Or get rid of the daily restriction, so if someone wanted, they could spend all day just grinding explores of there level to get dilithium ore.
Currently there is not enough ways in lower levels to get even close to the 8000 refine limit, so opening up explores back to every 30 minutes would not have any impact because of the refine limit!