If you want Bitlocker to protect against someone stealing your laptop, you should be using a password anyway (and disable non-hibernation sleep modes).
(Also, this is just offensive levels of dumb—why is the key material just strolling along the bus here in plain view? There isn’t even a key exchange protocol or anything.)
[1] People are also talking about secure erase here, which, okay, is weaker, but FDE + a EEPROM in a socket that you can pull out and physically destroy does that part just as effectively.
You can configure a dedicated password for bitlocker, or a pin (can be alphanumeric) in addition to the tpm, but there's no link between that and your windows account once the os is booted.
I think MS' point about the standard bitlocker setup is that people can't just steal the drive and mount it in their own PC, they need your specific PC. And also, that windows is secure enough that if you have the correct PC with the drive and the OS boots, you can't open the windows session (which by default requires a password). So in this context, bitlocker adds some security while being "transparent".
This article, however, says that this setup does not protect the data at all against a thief willing to pay $100 lifetime (not per machine), which seems an absurdly low bar. (And I’d wager you can go even lower by wiring up a cheap devboard—basically everything has a SPI peripheral these days.) I mean, liquid nitrogen is not exactly expensive either, but it does require some fuss, whereas the attack in TFA could be made essentially as easy as opening the case.
But I still can’t get over the idea where the default configuration of BitLocker is completely useless for basically anything except working around storage devices that will lie to you and not erase things you told them to. I just refuse to accept that’s in any way sane.