Sure, your business documents are seen by a far smaller audience than your marketing materials, but they’re still part of your brand. Documents based on generic forms can certainly show the required info, but when you use them as-is, you’re missing another chance to make an impression.
Your invoices give you another opportunity to extend your brand and stay in front of your customers. Show them that you put as much effort into the behind the scenes stuff as you do to your social posts, site content, and marketing collateral. Do the little stuff like you do the big stuff — go big or go home!
Granted, the look of an invoice probably isn’t going to get you a bunch of new customers, it’s part of the overall look you want to portray. Why not make it look great?