I think some players would prefer to know exactly what all the prices will be and how much gold they will get per level so they can predict exactly what items they will get and incorporate that into the character-optimization mini-game.
Other players prefer to use item-acquisition as a motivation for adventuring and social-interaction. For them the vague pricing works better because finding out what price the DM will set is actually part of the game. That price may be in gold, bloodshed, rare arcane ingredients, or my favorite, promises.
5e leaves item prices vague, setting an important player expectation that DM's discretion will set the final price, and that the player's can't predict ahead of time what the prices will be (and there are no gold-per-level guidelines either). If players want predictable pricing, so they can browse magic items like a catalog, then that IS a lot of work for the DM.