Of course if you’re not a signer and aren’t interested in singing then the aesthetic quality of singing shouldn’t be scored, and hopefully they were also teaching you a little bit about how to sing, or maybe you just got unlucky (sometimes there are crappy teachers, bad exams, unfair situations, it does happen unfortunately). Singing really is a very useful skill to have when playing instruments or teaching music though. I wasn’t interesting in signing when I was younger, but now I wish I’d spent more time learning how and didn’t have to hide in private to be comfortable singing. It does something very interesting to sing & play at the same time, it’s hard but I think it makes playing the instrument easier.
There are some problems with complaining you’ll never use a certain skill teachers are trying to teach. Specifically, you don’t know in advance that you will never need it professionally. More generally and more importantly, the whole point of a university education is to give the student a broad base foundation in the subject, to teach you more than a small set of specific interests, and more than is required for a specific job. It is intentionally designed not to be strictly vocational training, it is not an apprenticeship.
I made this mistake when I was young, and complained in a math class, joking loudly and publicly, that the teacher was wasting our collective time forcing us to learn esoteric things we’d never use. I don’t remember what it was exactly, I think maybe matrix determinants, and the joke’s on me because I use determinants and everything else the teacher was teaching in my job professionally.
BTW, I work in chip design and all the hardware people know and use sorting algorithms, and not just the kind you learn in CS 101, they are experts in parallel sorting algorithms. Put the death of Moore’s law on top and the fact that algorithms and efficiency and power consumption are becoming more important every day. These foundations that students assume aren’t relevant to the future actually are important to their future prospects, they just don’t know it yet.