You get 2FA via Authentication Apps which is sufficient for most, and there is extra security for those who need it.I always find it ridiculous that such a important feature is only available for pro.
Buying a YubiKey isn't an investment for everyone, in fact it costs more than 1 year of LastPass Premium.
Please note to work with LastPass, you will need a YubiKey 5 Series key.
A lot to multi-tier solutions add extra security and privacy features to paid / Premium tiers.
Privacy-based VPN example : ProtonVPN Plus has Secure Core whereas Free does not. You pay for the extra measures.