The problem in many parishes is vandalism and theft. The exposed Monstrance is quite expensive and a prime target.
Our tabernacle is in the center of the altar space, but it’s locked and I’m willing to believe it’s bolted down. We also have an adoration chapel. It’s not easy to find if you don’t know where to look. That’s where we have the monstrance. We also are supposed to have someone there 24/7. I visit our Lord both places.
Well... they could lock the doors until the next Mass, couldn’t they?