hmmm.... I am not sure about the safety issue. Normally a pilot that knows how to hover an airplane right over a runway will most likely know what he is doing and have control over his plane. After all he is risking his plane and himself also.
However, it should not be done if other people are flying at the same time. Hovering an airplane is really not as hard as it looks, but is a nice crowd pleaser (specially to those who do not know how to hover or are just spectators).
I guess I could agree and think it should be done with precaution like everything related to this hobby.
If we would list all the dangerous things we do at the field (and sometimes in our workshop) we would probably fill pages here
Just my $0.02