I was(am) one of those players. I didn't just have items along top of inventory. I also had food and water on right side. Some ores in second row and some items like feathers along the bottom. So this system works well for me.
I have only tried it for a few minutes in a test game but I can see how sometimes it is hard to see the lock icon. I am guessing a modder will have something soon where you can pick a colour.