networking – IPv4 Address Range Shortage Inquiry

Recently I was looking over RFC6890 (link here) to find out more about the current IP addressing schemes that are in place and noticed a rather large IP address range that is listed as “Reserved For Future Use”.

The IP address range in question is 240.0.0.0/4.

Since IPv4 is currently running out of available address (hence the transition to IPv6) why wouldn’t the IETF open the 240.0.0.0/4 range to the public so that it could be used as public IP address space? I know that it won’t solve the IPv4 limitations and I know that one day we will eventually run out however opening it to the public would give an additional 268,435,455 IP addresses which in my mind is a rather substantial amount that as of the moment is just sitting there doing nothing.

Is there any particular reason that it isn’t being used for public allocation?

A secondary question that I have is why is the loopback IP address range (127.0.0.0/8) so large? As of right now (and I very much doubt it will ever change), the loopback IP address range is 127.0.0.0/8 which is 16,777,216 IP addresses. What could we possibly need 16,777,216 loopback addresses for? If you have an answer for this could you please let me know?

Thank you.