Because bits are not expensive anymore, and if we used 64 bits, we might run out faster than the time needed to convert to a new standard. (After all, IPv4 is still around 26 years after IPv6 was drafted.) Also see the other notes about how networks get segmented in non-optimal ways. It’s a good thing to not have to worry about address space when designing your network.
You can get Mint on a “Live” USB flash drive, so you can boot it up and see if it handles all your hardware before you install anything.