Why is seemingly everyone on the forums assuming the damage system is final and never to be changed? I'm not going to deny that the current system is lame and nonsensical, but that is also why I strongly believe it is only a half finished feature to be replaced in the future. The game was rushed to meet the release date, I very much doubt tripwire is happy with all aspects of the day 1 release.
At present, there is a detailed indication where you are hit and how severely (undamaged, yellow and red) but there appears to be no features taking advantage of this detailed damage model. Obviously, the intention was to at the very least be as detailed as RO1, but pressumably the feature was not finished in time for the release.
The bandaging system is rather inconsequential. You get wounded, you have a few seconds to hit CTRL to stop the bleeding. Sometimes you are in a position where you want to find cover before bandaging, which means you may bleed out before you can stop it. Most of the time however you just hit CTRL right away and a second later you are ready to keep on fighting. Lame, and obviously, not a finished feature.
I don't think the act of bandaging yourself is there for immersion or anything. If made entirely realistic it would be an incredibly boring and pointless feature. What it does however is making the damage model more detailed and less simplistic. You are not going to get killed from being shot in the hand with small caliber guns which is a flaw in many realistic games that goes with the "1 hit, you're dead" model. That is lazy.
Once fully implemented, bandaging will become a way for the player to get hit from sloppily fired shots from unseen enemies without recieving a cheap death and being forced to respawn. Imagine having an MKB user spraying randomly through the walls of a building and killing you without knowing you were there. That would be incredibly frustrating, but it would also be frustrating if you could hit people several times over and they won't die from it. Bandaging becomes the middle ground, it makes it so you don't need to be 'randomly' killed by sprays of bullets, but it also makes it so that every hit does have some kind of consequence, if only not a frustrating cheap death. It takes you out of the fight, but not as long as it would take having to respawn and get back to the front. A middle ground.
Once fully implemented, that is. As of now, it is just some very basic framework for a future addition to the game. A placeholder feature until the final model is implemented and ready for tweaking over the coming years.