There is a massive middle ground between "chasing after" and "actively attempting to alienate," especially when you're dealing with an interface technology that is quite literally decades old. It's not like people are asking them to get room-scale VR working perfectly here. Hell, from what I've read, the game doesn't even support using a mouse to navigate its menus, which is a pretty damn low hurdle to clear.
And while the "mass market" may not care either way about joystick support, the smaller enthusiast side of the sales bell curve provides a great deal of value as well, particular in generating and maintaining enthusiasm and interest in a title. Most developers don't tend to be in the habit of driving away decent percentages of their potential market. Surely Bandai Namco had to realize that there's a pretty large overlap between "people who play flight games on PC" and "people who own stick/HOTAS setups."