There are many reasons to not address ports of switch by MAC.
MAC number is stored in hardware (read-only memory card). If each port address by its own MAC, it also has own ROM card => more money on hardware
More complicated when you config MAC address table of switch manually.
Exhaust MAC address resource faster, then you have to register another OUI number (Organizationally Unique Identifier)
You can see an example of MAC address table of a Cisco switch below:
VLAN MAC Address Type Age Port
---------+-----------------+-------+---------+--------------
1 0018.b967.3cd0 dynamic 10 Eth1/3
1 001c.b05a.5380 dynamic 200 Eth1/3
So you don't need separately MAC address for each port to make your switch work.