I think CEX cannot force Memo when users want to transfer crypto assets because users may still need to transfer tokens to a self-custodial wallet rather than a CEX wallet address.
Exchanges are not always able to remove the "Memo Tag" field from the deposit form. There are several very useful functions of Tag Memo, especially for centralized fund management.
From my PoV, memo tag request is the right thing to implement in CEX which means the exchange generalizes the user's possible risk of sending mistakes. After all, self-custodial wallets can also generate Memo (afaik). I think in this kind of coin activities, users should include a Memo wherever they send their coins.