Reasons to incorporate include 1. limiting your liability and 2. establishing a formal agreement between you and your friends. First, if someone were to sue your company and you weren't incorporated (LLC, C-Corp, etc.) then they would be suing YOU personally and you would be liable. If you do incorporate, someone suing you is actually suing the company - the company is liable and only in specific cases can you be personally liable.
The second part is that incorporating typically puts out the terms of your arrangement with your friends - right now, if the hosting is in one person's name, they could essentially be the sole owner of the company (unless you had a lawsuit over IP, or something like that). Incorporating makes clear that the company owns the site and IP, and decides what percentage each party owns of the company.