Eh? People just pay for their stuff. The problem is there isn't really a market for OSes (as a consumer), period. Unless you build a PC yourself, which is not the norm, you don't usually even buy an OS.
This has nothing do with whether the linux audience pays for stuff or not...they pay fine. It is true that it is relatively niche even for linux folk to want to do this sort of thing, but that has more to do with laptop vs desktop form factors than the market. If it were a common need, I think it would be a common thing found on the market. In fact the existing ext4 stuff for Windows indeed used to be paid, but this was primarily for Windows users, Linux users have had no issue accessing ntfs drives for ages, and generally didn't really enjoy giving Windows access to their drives anyways, what with the market for viruses and whatnot...
GNU philosophy is not about moneymaking or footing the bill. Sometimes a problem gets worse when you throw money at it.
I am probably in the minority of Linux users though.