I think you're totally right from a practical view. Trying to debug 16-bit x86 code is a nightmare, none of the debuggers properly support it.

Leaving practicality aside and focusing on aesthetics... Normally, for hobby wheel reimplementation projects like this, I find doing it as close to the bare metal as possible, relying on the minimum amount of other people's code, a lot more fun.

But AFAIK, these days legacy BIOS boot is just some emulated compatibility mode running under UEFI anyway. The bootloader already ran and configured the hardware for you, and then it un-configured a bunch of stuff so you can re-do it. It's role-playing as an 80s PC for you. I find that deeply unsatisfying.

UEFI is the bare-metal API, for all intents and purposes. (Unless you want to go completely blobless, writing your own firmware.)