I don't know. You should ask this from yourself.
The question is why someone would freeze a used address, so that electrum doesn't send the change to it? If an address is used, you will never get that again in request tab.
The other question is why someone would freeze a used address, so that electrum won't propose it as a receving address? If a change address is used, it will never be reused for receiving the change.


You said "If you freeze an address Electrum won't use it to send change and it won't propose it as a receiving address" and as I said, your statement is completely wrong.
We freeze an address, if we don't want the UTXOs associated with it to be spent. The freeze address feature has nothing to do with what receving address electrum will give you or what address the chane will be sent to.

If you request for a new receiving address, electrum will give you one of unused addresses and it will never give you a used address.
If you make a transaction, it has a change and you haven't disabled the use of change addresses, electrum will send the change to one of unused change addresses.