It is certainly not unheard of for repetitive flight plans not to be updated after an aircraft type change.
To add to my colleagues, also from a tower perspective, your aircraft type can be important for ground restrictions, specifically taxiways and parking stands. Generally a discrepancy will be spotted on the deck, once in view of the tower, but it's not impossible to sneak the wrong aircraft all the way into the sky before anyone realises. Inbound of course, the wake turbulence category is important long before you're identifiable to the tower.