You will win new business. A well-written pitch will stand out – many are awful. So it will get you in front of new potential clients, so you can persuade them face-to-face that you deserve the job.
You will enhance your reputation. Every piece of writing, however short, affects how clients think of you. Well-written advice is striking: they will come back for more.
You will become more efficient. You don’t want experienced professionals to spend valuable time correcting juniors’ poorly-written drafts.
You will minimise risk. Clear writing and drafting avoids the misunderstandings that lead to client disappointments, or worse.