Since #34 is now resolved, it is safe to set hideRecipesIfMissingResearch=true, which I believe makes the game more immersive.
That being said, new players can get confused when nothing shows up if they look up recipes of many Thaumcraft-related items.

In 1.7.10, a relatively recent mod (GTNewHorizons/TCNEIAdditions@e98247b) added a feature to show a message when research is missing, so JEI (or NEI) will still display something.

Would be a really great (small) feature to have!