SB is definitely imperfect, but a useful tool in moving toward a trusted boot. I think we'd all agree having a trusted boot sequence is desirable, the point of contention being who gets to decide the criteria for trust. It's been a few years since I worked in the space but I think SB gets a bit of an undeserved bad rep (I'm sure because people were vocal early on). There is a SB signed uefi application that allows for enrolling other loaders based on the hash of the loader.