Actually, it's both, and there are plenty of people who act Shakespeare but don't have a clue what he's saying and others who do nothing but read him but can discuss him fluently.
he wrote plays--they are plays--to be played---The French considered him so vulgar that they cut the gravedigger scene from Hamlet, in the American west the endings were changed to happy endings--Cordielia recovers and is reunited with Lear-----the interpretation changes with each generation---but what is truely transendental about his work can only be appreciated in acting or watching his work acted out. I do suspect its is better for the actor than the passive watcher. My opinion only of course but it does come from personal experience.