I think a low cost display is more important as a camera.
Not much to see with an camera and no display
Many will disagree, others may agree. A lot of hobby projects (mainly robot-oriented ones) will not require a screen, but they do require a camera. Programs can operate without a screen.
The Foundation's goal is to release a $25 "linux box" (a small computer that can run linux and python) for teaching how to code and to renew interest in computing. Their intention was never to release a complete computer including keyboard, trackpad, screen and other peripherals (like One Laptop Per Child basically did). The assumption is that the user will already own an HDMI, DVI or composite-compatible screen or television, apart from a keyboard, mouse, SD card, etcetera. However, USB cameras have never worked properly due to the low transfer speed of usb (it's too slow for raw video), so it'll be a nice addition to release a camera which is compatible with the raspberry DSI connector and GPU architecture