I think there should be bigger and wider space for writing the buyer request. Its really annoying that the space is too congested and its also quite difficult to select one word or line there. It always select the whole para and hence require more time to complete and sending offer.
Welcome to the Fiverr forums.
I suggest composing the offer in a document on your desktop and copy/pasting it into the BR text box. Notepad is good for this, since you can’t include any formatting in offers. Just be sure you read over your message for any errors before you send.