This is one that has been reported on for awhile now and never changed or fixed. Razor wire should be one of the top things you build as a defender if it worked where you needed it. Doorways, gaps, bushes, common entry routes, and even just gaps in other compositions. Razor wire is cheap, quick to build, noisy, and has high utility against basic infantry intrusion. But the limits in where and how you can place it just lead to it never being built, that and the fact that it still breaks itself after 30+ seconds.
As Chaos points out it has no negative effect on players and is easily mounted.
Cuts would offer a risk reward scenario as well as a tactical one for the player. Do you choose to try and get through the wire, or do you avoid it? With the current attack/defense meta being a glorified cat and mouse game, razor wire would add a lot of depth to that as well since you could set it up in known positions and again common entry routes like doorways and fence gaps.
Razor wire still does not function in Conflict. I just tested this today as of 10 minutes ago.

On the previous update that happened to me, but on the current one it has never happened afaik, it always stayed built.
I've seen the reports and it says resolved. Probably because people could jump over it like a normal fence before but now they can't - unless if they are on a slightly elevated terrain or on a rock like I mentioned on the post.

I did some further testing in GM mode instead of Conflict. Razor wire does function in GM, in that it will remain where you place it. Unfortunately it appears to be indestructible to using explosives, melee, ore small arms, though you can still drive into the wire to destroy it.

Including some pics of places i would use razor wire and use cases. I'm using Coastal base Chotain as an example as it's a base that often is easily intruded on. Obviously not all of these are going to be realistic or practical for Conflict. But having more utility overall would be the idea. Forcing attackers to make more noise and have fewer places to hide would help defenders who utilize defenses tactically. Likewise attackers would have to utilize explosives as breaching tools more often, leading to those being used less on infantry (hopefully).

Used to deny access to the rear entrance of '3 story'

Again these were placed in GM, as most spots are not possible in Conflict.