Definitely agree on this one, you almost have to look for the DvL bosses as soon as one side enters the victory state in order to be able to get the kills, and as mentioned on DK it's still near impossible to get them because most of the bosses spawn in questing area's or beside Heroic 2s.
Secondly the Victory state especially at weekends tends to happen in the middle of the night, so unless you have a group of very patient insomniacs sitting there at 3 or 4am then it's unlikely you'll get a group together in order to kill them.
I also cant understand why the decision to change the duration of the victory state from 1 hour went so drastically to 18 hours. 6 or maybe 12 hours would be better.
I would suggest that as per the OP's suggestion, either the bosses are given a respawn timer or shorten the victory state.