The 1 or 2 kB of lyrics are a few orders of magnitude smaller than the song being streamed.
The album art probably takes up more space than the lyrics.
So, album art should also be a paid feature?
Album art would make way more sense as a paid feature than lyrics, considering it’s a largely cosmetic improvement.
How does it make more sense that “cosmetic” features are in the paid-tier? Would it not be the other way around?
Because it improves the experience, but isn’t vital to it. If you want the free tier to be accessible to everyone, limiting things like lyrics that people like OP use as a disability accommodation isn’t the way to do it.