To simply put, it's quite archaic that the Project Description does not have the ability to preview the description.
Having a Preview button would mean saving on constantly having the page updated publicly on a frequent basis. The editor suffers a lot of problems and some changes on the description don't get reflected on publishing, so it would also be very useful for navigating editor bugs. It would also save on embarrassing changes, such as accidentally turning the whole description into HTML span elements, or fidgeting around with whitespace formatting.
Thank you. This feature is something that we're looking to add as part of the new website coming out this year