Frankly, I think the expectation of being able to save everything for later is just silly. You will never have enough room. If it upsets people that they "sold something that I'll need later", then realize that damn near everything has a use. And you just can't save all of it.

And so much of the crap doesn't need to be saved. When you are just starting out, it's so much easier to sell the stuff, and buy what you need, when you need it, later down the line. Saving a stack of crafting material doesn't mean a whole lot when you need 30 stacks of it down the line. Or 100.

And the longer you play, the easier it gets to make money and buy what you need. Or to use the money to buy more bank slots.