honestly speaking, I go with the suggestion that the site should get a revamp, I agree that sometimes, somethings are better left as it is, but not in this case, freebitco needs to update their design, the look is too outdated, it does not fit the accomplishments freebitco have made in this several years, they need to update the design of the site to something more modern.
Or here is another idea, if they really love this design and don't want to loose it, they can design a new version of freebitco with a modern design and conjoin it to the current freebitco, then introduce a button through which users can switch between both designs, they can name the current design "vintage" since it look old school, and name the modern design "classic", this way, users get to choose whether to have their freebitco account operate in vintage or classic mode.
I do agree with multiple pages type of deal. That way you could either use the old one or the new one, that is purely dependant on you and whatever you pick. That way they do not have to really force anyone to do anything they do not want to do. I know that not many people really have any type of reason to leave just because the design changed, but I am pretty sure there would be plenty of reasons to join because the design changed.
I have been here far long enough to know what has happened in its history, and a big design change is not one of them. I am afraid that if it keeps looking like this for another 10 years, there is a potential threat that people may leave for things that look better, or more mobile responsive.
Personally I go for the nostalgic sensation. I like the site exactly how it is because it remains loyal to its early years, which also remind us very positive memories and emotions from a time when Bitcoin was cheap, had a lot of growing potential and it was easy and simple to acquire large sums of satoshis through the use of faucets. The currently freebitco.in's design is like a sweet memory from a place, situation or object from your childhood which you remember with a lot of affection and kindness.
Maybe it's not so interesting and looks old-fashioned for the new users, therefore developers have to take every aspects into consideration and weight all of them to reach the best conclusion from the site's sustainability and prosperity point of view.