That's because that's how the site actually looks, as does ICC by the way (beneath its slicker interface), and always has going back to 1995 when I believe both were founded. Both FICS and ICC were based on the original ICS site and after a disagreement broke out between the founders about whether or not it should go commercial, one of them departed and took the ICS code with him and founded ICC.
The others eventually cobbled together the original ICS server code and re-opened the free site under the new name FICS with the founding principal that it would always remain free. Anyway there's a lot of different interfaces you can use to play there with varying degrees of server command knowledge required. Although you don't need to know that many to just play games there, and there's help channel there to help you along.