They only asked for one thing. The guidelines are why you win, not why you waste time.
"They asked for a newsletter. Making branding guidelines on top feels like extra work for nothing."
It is the opposite of nothing
The short answer: branding guidelines are the clearest way to show a client you understand their business. On my trial, the client asked for a newsletter. I made branding guidelines too, so the client could see that I really understood their brand, and so my newsletter would actually fit it. That proof is what helped win the job.
It works on two levels. First, the guidelines make your actual deliverable better, because now it truly matches the brand. Second, they are a visible artifact that says, before the client even reads your work, that you took their business seriously. Most applicants do only what is asked. The guidelines are how you quietly outwork them.
The branding guide is proof of understanding, and proof wins trials. It is not extra for its own sake. It is the extra that makes everything else you deliver believable.
Hold steady, BFF Team. We keep going together.
– Lala