If you look at the last link i provided it should provide all the information, including reasons why you should use css over tables.

Some of the reasons are things such as reduced file sizme, support for disabled users (i think tables can affect the way data is read when using web page readers).

Also as i said using tables makes placing dynamic content (either JS/Ajax or just PHP) more complicated.

Another reason is redesigning and maintaining site design consitency is more difficult, where as using css it is simple (sometimes just a case of a different css file)

Also using css allows sites to be redisigned totally just by using a different stylesheet instead of recoding lots.

Edit: Also i wouldn't count using more advanced CSS a workaround as when you start learning HTML you don't know tables to start and probably just use paragraph tags etc. then you find tables and use them, maybe that can be considered a workaround as well ?