What if I want to try play differently, you can learn all power and change class? If the combat is so shit, then I can do whatever I want as a character just for the lolz and equip it as a clown.
Even if I don't plan to ever use it why would a game that is not about ressource management block you from hoarding anything I want in a chest? At the time of flash for CoC1 and TiTs I could understand the limitation of programation on infinite storage but javascript doesn't impose such limits.
Now let's imagine somebody didn't keep all the useless items they got and only kept what they are currently using and one or two change for specific case, they would be right now in the impossibility of interacting with the new, not really worth it, character. I guess it would be an exceptinnal case and most player decided to keep shit even though the game doesn't encourage you to do so.