I like the 3.5 weapon sizes, and while I'm generally in favor of K.I.S.S. design, I hope that they're retained.
One of the things that drove me crazy about 3.0 was naming weapons for increasingly larger creatures. What do we call the equivalent of a longsword for a gargantuan creature? "Gargantuan Longsword" (the 3.5 answer) makes... a lot of sense, and saves us from having to make up a new name for it, then do conversions up and down when other creatures attempt to use it.
One of the things that drove me crazy about 3.0 was naming weapons for increasingly larger creatures. What do we call the equivalent of a longsword for a gargantuan creature? "Gargantuan Longsword" (the 3.5 answer) makes... a lot of sense, and saves us from having to make up a new name for it, then do conversions up and down when other creatures attempt to use it.