I’m torn on the free user part. I don’t like the idea of charging money for account security features. To my knowledge, Yubico OTP has no phishing resistance; unlike WebAuthn. Also, not everyone purchases their security keys at anywhere near $45. Microsoft and Cloudflare have had promotions with Yubico, making them only $10 per key. There’s also other cheaper security keys that support WebAuthn. However, I recognize that it’s very unlikely for Bitwarden to change this, since Advanced 2FA is listed as one of the premium features on the home page, and likely other areas.
I have upvoted the below thread. I have a few YubiKeys stored at my residence, and then a couple stored at various other residences of family members. It’s very easy to surpass the five key limit, especially if you’re using a phone that doesn’t have NFC (my immediate family all have > 2020 Motorola phones that don’t support NFC). Then you need to get multiple USB C security keys and multiple USB A security keys.