If you use the Rayleigh criterion to calculate the maximum angular resolution based on aperture (θ = 1.22 * λ / d) using green light for the wavelength (and focal length / focal ratio to get the aperture) and use the resulting angular resolution and the given diagonal 84 degree field of view... you end up getting that there are about half as many pixels as the maximum theoretical angular resolution. Combined with lens imperfections and other sources of distortion (as opposed to the other commenters talking about exposure times) the result is that the extra pixels are really probably not adding any new information, or that they're right at the levels of diminishing returns where the returns are more or less zero for extra pixels.
>can you always get value if you're willing to bump up your exposure time
No, there are hard limits on how much extra information you can get with more exposure time.