phpBB is free software and it can be easily customized. If looks are the problem (and I would agree on that), that can be easily changed. Take a look at this for example.
The emojis are also awful and dated, and so is BBcode (there is a plugin for Markdown support). I propose (and am willing to contribute as a coder, within my constraints of time and skills) to work on the existing code base instead.
People wanting "a more modern layout" can use a personal userCSS:
- Huge font sizes
- Big "scroll-to-death" spaces
- Hardly readable but beautiful Webfonts
- Random pop-ups getting in your way telling you stories about cookies and new articles
Thinking about what today's webdesigners' "good design" is this version of linuxmusicians.com doesn't look so bad anymore:
http://www.wonder-tonic.com/geocitiesiz ... icians.com
Well, if we are active users here I think we don't mind the looks! It's more about attracting new users.