Items obtained from crates are purely cosmetic and offer no advantage to players. In fact, wielding a colourful each catching weapon may even give you a disadvantage in that you stand out more to the enemy. It seems a cheap way to get money being that it's simply a form of gambling but they have done it the right way in that it's not P2W.
Valve discovered that you can make money just from people wanting to be special and show off in games by having something nobody else does. They make millions from key sales alone and it's also a nice earner for those who get items accepted into the game (£30,000+ almost guaranteed) just for a weapon texture paint over.