To be fair I understand why they did that and I'm very happy with how they handled a spell-less bard. The writers have stated that they wanted to make each character feel distinct and needed, even from the eyes of someone who doesn't know anything about DnD. The way they handled that was to make the sorcerer the only spell caster so that no other protagonist could cast spells and weaken his importance to the group dynamic. To remedy that they leaned hard into bardic inspiration. While it's never said and never made explicit, it'sso clear to me as a long time DnD fan that the bard is constantly rolling bardic inspiration die. Honestly I think it brings out the unique strengths of his class more than if he was also casting spells, which is what I think the writers were going for.