But using IR requires more componentry added to cameras, no? Specifically IR cut filters.
Well, technically a visible light camera would require an IR cut filter more than an IR one, i.e. all the time, right? If you mean it wouldn't need the expensive (relatively) mechanism to switch it in and out of the focal plane, I'd agree, it wouldn't.
On the other hand mechanical IR cut filters are not present on a whole swath of lower end cameras which have IR. They just limp along with some lens coating which cuts out the longer wavelength IR, but leaves the rest as a compromise. (As you know that's why they can't really be focused that sharply.)
Again about the color temperatures being offered, these are combinations of LEDs and therefore not as cheap as a single diode, nor as efficient. Ditto the added cost in $ and lower efficiency for diffusers, as they absorb light to some degree.
And in any event it's just really hard to make a wide beam out of a directional point. And it's wasteful anyway to provide light outside of the FOV of the camera.
A couple of other observations:
Sensors are notoriously sensitive to IR. My guess is that in terms of apparent brightness, IR provides more illumination per watt. I'll look for some evidence to support this.
Finally, visible illumination is a visible give away to what a camera can likely see at night, where IR keeps you guessing, unless you have a cell phone.
Related: Does Your IR Illumination Advertise Your Blind Spots To Criminals?