Well, they have to convince people to buy it during the first weeks after release. You're talking as if the first print was some super special collectors club edition that costs you a kidney and your firstborn. The manga itself is about 4 bucks and shipping should be another 4-5 if you choose SAL. Overall that's less than what you pay for some translated manga.
If you can't afford that it wouldn't bother anyone if you asked once or twice, but that constant whining, crying and complaining is off-putting. That stuff will get scanned eventually. Asking for it over and over every time there's a new volume won't make the mail arrive faster.
Kind of related. Shogakukan finally included most cover illustrations in their digital release of volume 5. Only the pink illustration and that small bit on the book's spine are missing.