Did anyone really think that making UEFI systems the equivalent of a mini OS was a good idea
UEFI and Secure Boot were pushed forcibly by MS. That's why FAT32 is the ESP filesystem.
If I had to guess, a brief was drafted at MS to improve on BIOS, which is pretty shit, it has to be said. It was probably engineering led and not an embrace, extinguish thing. A budget and dev team and a crack team of lawyers would have been whistled up and given a couple of years to deliver. The other usual suspects (Intel and co) would be strong armed in to take whatever was produced and off we trot. No doubt the best and brightest would have been employed but they only had a couple of years and they were only a few people.
UEFI and its flaws are testament to the sheer arrogance of a huge company that thinks it can put a man on the moon with a Clapham omnibus style budget and approach. Management identify a snag and say "fiat" (let it be). Well it was and is and it has a few problems.
The fundamental problem with UEFI is it was largely designed by one team. The wikipedia page: https://en.wikipedia.org/wiki/UEFI is hilarious in describing it as open. Yes it is open ... per se ... provided you decide that FAT32 (patent encumbered) is a suitable file system for the foundations of an open standard.
I love open, me.