Because we love Hagrid. We love his heart, his love for dangerous creatures, and his terrible cooking. His height is just part of his mythos. He's big, he's cuddly, and he's fiercely loyal.
Knowing that Robbie Coltrane was "only" 6'1" doesn't ruin anything. If anything, it makes the performance more impressive. He acted bigger than his body. He moved like a gentle giant, even if he was just a normal-sized guy with a fake belly.
So, next time you re-watch the first film, look for the tricks. Watch how close the camera is to his face. Notice how the kids seem to be looking up. It's a beautiful lie, and we buy it every time.
The Final Answer (For Real)
If someone asks you, "How tall is Hagrid in real life?" you can say, "Robbie Coltrane was 6'1"." But if they want the magical answer, tell them he's as tall as a giant's dream and as wide as a warm hug.
Either way, you're right. Hagrid's real height isn't in inches. It's in the size of his heart. And that, my friend, is truly immense. Much bigger than any camera trick could ever fake.
So, go grab a butterbeer (or a coffee, like us) and raise a glass to Robbie Coltrane. He made us believe that a 6'1" man could be the most lovable half-giant in cinema history.