Even having no pre-boot PIN with SB on is nice, then you only need your user space login where you could even use fingerprint reader if you like. For servers they can already start serving without anyone having to intervene manually (which is nice after power outage, for example).
So yeah, SB, TPM and FDE are a very nice bundle that heavily secures against the most relevant attack vectors.
The main advantage of SB is TPM. At runtime the key isn’t available and unlocking your disk works automatically as long as nothing has been tampered with (which is then also a nice canary: if you suddenly have to enter your password during boot, something’s off).