causing inconveniences for legitimate, paying customers (even if they're buying from a market you dislike)
End of quote
The problem being that in all technicality, they're not legitimate customers. Do you know why companies like GameStop currently have money coming out of their ears, and why game developers hate them? Because they're not legally required to give ANY money to the game publishers - and they don't. When you buy a used game not a single cent of your purchase goes to the company - and as such, no, I don't feel they're obligated to provide any sort of support whatsoever. Maybe if MORE companies took that stance we could actually, I don't know, get some laws enacted to be a bit fair to the developers.
And to anyone who says "but people buy and sell used items all the time and never have to provide any money to the companies" - yes, that's true, but that statement generally applies to non-digital items, and it is usually understood by people that there is a consequence to buying used. If you buy a used car, it has more mileage, a shorter lifespan, is more prone to breaking down, etc. When you buy a used book, there may be pages torn out or writing in it or just general wear and tear. For most of the items that are sold used, there is a downside.
When you buy a used game you get the full product in pristine condition. Moreover, GameStop pays people 1-3 dollars for most games and then turns around and sells them for 20-40. They are raking in money and it's seriously harming companies, as it's very common for people these days to buy a game, play it and then turn around and sell it when they're finished.
I know it sounds mean but I'm all for watching the used game market go down in flames, before every company has to merge with EA or Activision to survive.