While you post good advice, more people see your car on a daily basis than the amount of people who would ever likely see it online.
After all cars are recognized for their features and rarely for their numberplate.
You never go to a show and say "Ahh man, yeah that Mk2 that had the registration A418 KJU..." - You're gonna say "That Mk2 on 3 piece BBS splits and custom interior with an R32 engine"
We have insurance, alarms, trackers and what not for a reason.
If we spend all our time worrying about who sees our photos than actually just enjoying the forum and user environment then we may as well not bother posting photos without Photoshopping the wheels, interior, etc. As people recognize cars from their appearance.
A poorly edited numberplate removal can completely ruin a picture.
Ultimately the choice is yours but a registration plate on it's own gets you nothing.