Part of what makes this work is its sincerity. If Woody Allen made this even ten years earlier, he might have starred, which would have been a worse movie: every quip he makes in his films somehow sounds cynical (and sometimes cruel).
On the other hand, Owen Wilson’s wide-eyed, “oh shucks” performance is affable and earnest. He doesn’t act like Woody; through his eyes, we see Paris as charming and nostalgic, not unlike him. He puts heart into it, and completely sells the illusion.
Perpetual golden lighting only helps romanticize the illusion, and it makes Wilson’s performance appear even more sincere. In our current era of cynical filmmaking and superhero cash-ins, this goofy little romance remains a breath of fresh air.