You are discouraged from installing decorations/furniture that leave permanent marks from the room and doing so leaves the risk that you will be fined for damages at the end of the year. That being said, no one is going to stop you. If, at the end of the year, you remove it and repair your holes, you will be perfectly fine. No reasonable RA will make you take anything like an organizational hook off of your wall. I would say that you should hang your bar/hook if you want it – better to be comfortable in your space and deal with the repair later!
I might recommend that you check out 3M strips and other alternatives – they may do the same job and be easier.