tap(4): will it be more reasonable if it preserved UP/DOWN state, when closed?

[Yuri]

Currently tap(4) device gets to 'down' state when the last process 
closes it, regardless of the original 'up/down' state.
Will it be reasonable to modify this behavior and keep this bit 
'was_up_before_open', and leave it 'up' if it was 'up' when it was first 
opened?

Practically speaking, I set it up in rc.conf to be 'up' with the 
particular IP, but it goes to 'down' state  when VirtualBox closes it.

If tap(4) can be 'up' without users, there shouldn't be any problem in 
leaving it 'up' after use as well?

Yuri