10 Reasons We Need Java 3.0
Subject:   byte primitives should be UNSIGNED
Date:   2002-08-04 18:37:57
From:   bchapman
If byte is only used for I/O and memory operations and dropping the math operators from it leaving only the binary operators is a good idea , THEN it should also become UNSIGNED.

As for the assumption that bytes are used for non arithmetic things only, its probably a fair assumption if you are going to redesign the language.