It's an actor's job to dramatise our projections, so from that POV he did a legendary job with TNG.
But there's a certain amount of learned skill involved. I know someone who used to work backstage at the Royal Shakespeare Company. She said that she'd all these famous names playing cards backstage, they'd get their call, turn on the juice, stride on stage, say their lines with the appropriate presence and gravitas, then turn the juice off again after the scene and pick up the card game where they left off.
Stewart's choice of roles and support for causes suggests there was more than that involved for him.
He wasn't Picard in real life, but he wasn't just acting either.
That said, Suchet's performance is magnetic but almost a bit too dignified to me. Stewart's take is not as handsome and agreeable, but makes perhaps more sense for Shylock - that raised-index-finger teach me moment is just sublime smartassery.
Suchet's Shylock is angry for being wronged, and rightly so. Stewart's Shylock is justifying his actions, and a little proud of himself for thinking of the justification. With modern eyes it's very compelling to side with Suchet's Shylock, of course, but it's perhaps not really the character. But then this duality is of course a great reason the play remains forever relevant and popular.