I wish they would take barbed wire out of the game as it does not stop zombies getting through and all it does is leave buildings with no way in. Can see it only as a mechanic by people to deny others from getting loot when they have logged out.
I have to go contrary to the majority opinion here.
Loot denial is exactly what barbed wire serves and I for one think its a relevant mechanic in an anarchronistic setting, of which DayZ is one. As politically incorrect as it will sound, I don't see anything wrong in denying survival items from competing survivors anymore than it is wrong to shoot some stranger you just met in DayZ just because you want his beans. I know I have been put in very precarious situations more than once because I ran out of food/water and by and large you cannot depend on most folks in DayZ to be charitable so I much rather kill them for loot or make it difficult for them rather than live in harmony with them.
I will however like to see them make barbed wire zombie-proof. Then at least it makes the item more valuable, versatile and purposeful and gives you the tantalizing hard choice whether you want to use up precious inventory slots to carry enough of it to plug up buildings with several exits and turn the place into a defensible temporary shelter. Some buildings have so many exits it is not practical to be carrying a lot of barbed wire, but still it will be a balance to carry some to cater for dwellings with lesser number of exits.
The current problem with zombies popping into buildings without opening closed doors needs to be fixed. There's more than once I waited for them to come in so that I can sprint outside again but got slowed down because I had to re-open a door which by right should have been opened by the zed.
 While on the subject, I think they should return the ability of zeds to climb ladders. I notice they don't climb up after the player anymore.