Because if you don’t support it you won’t be able to play any protected content on it which means no AppleTV, FireTV or any other TV box at least above 720p SDR.
Allow me to add that every time I’ve removed it I’ve had full licensing and permissions, just that HDCP was in the way.
Same goes for not supporting HDCP of a specific version e.g. a display that supports only HDCP 1.3 but not 2.0 will be able to display 1080 Blu-ray’s but not 4K ones.
Yes in theory you can rip it off however that is very expensive and difficult especially with more recent standards (I’m not aware of any way to strip HDCP 2.1 and higher) and bandwidths.
Also to strip it you still need to get a license and keys so it would be quite difficult to do so on a commercial basis especially in a country with strong rule of law.