Ok so the reason behind it is to show legally that no one is currently residing there but we are. If it's to make sure an eviction isn't hard, then it doesn't make sense as the contract with previous landlord would be transferred. The attorney for the buyer would know that it's in effect of the contract.
The only way I can see that is that the Tennant has less legal rights if not registered on the property. I don't know the eviction process in this country but in general I don't want to fuck myself by removing it. House gets sold the day after and a few days later I'm being physically forced to move out well before the time I have legally in the contract to find another place.