[alex7734]

I don't think it is that much more secure, given that in this case "something you have" is bolted onto the machine you're attempting to protect and that a sufficiently long password provides enough space to make brute forcing impossible anyway.

In my opinion all the TPM achieves in this case is ensuring you lose your data if the machine dies (or if some OS update fucks up and doesn't properly ensure the TPM acknowledges the new version as valid).

That said it does help against the so called evil maid attacks, given that it would lock itself out if anyone modifies the OS, so if that's part of your threat model then it is useful, I guess.

[bootsmann]

Even with a TPM the disk is still fundamentally encrypted with a key that you can make a copy off and put in your drawer for recovery purposes. It just offers a way to do FDE with no or just a low entropy passcode. This protects against most data loss incidents (laptop getting stolen) without producing massive overhead.