Custom Made

We're spoiled, us modern folks. We go into a store and they have shoes just in our size in a variety of colors. We go to buy a car and there, right there, are fifty or sixty cars we could take home. Shops and stores all specialize in one thing: stocking goods that other people make. You look at 'em and make your choices and then purchase what you want. Spoiled, that's what it is!

Medieval people, and by extension people in any sane kind of fantasy setting, don't have that luxury. If you want shoes, you have to get them made. If you want a sword, you have to commission it. If you want almost anything at all you have no choice but to wait around while it's completed. Cobblers don't keep a bunch of standard sized shoes, they size up your foot and make a wood mockup and then create a shoe just for you. Essentially, everything is custom made.

That means it takes time. This dovetails into the fact that healing, researching spells, and learning new skills all take time as well. Some new proficiencies should take at least a month of, if not several months of, uninterrupted study to learn. Guess what else you can do in that time? Commission a new wardrobe, get a new set of armor made, and have a smith make you a new sword.

Get used to it: things weren't always as convenient as they are right now.