then it would look crappy relative to capital letters "Ajax" - if the j bottomed out where the A does, it messes with the whole look. There's a whole world that we take for granted that typesetters/font-makers/graphic designers have figured out for us.
The question here was why they didn't use lower case letters exclusively instead of using upper case exclusively. In other words, if you have to pick one, why did they pick upper case instead of lower case? The difficulty of mixing cases doesn't apply to the question.
Exclusively lower case letters need more vertical space than exclusively upper case letters. "fgjl" has the same "top line" as "FGJL" but has a bottom line that's at least two pixels lower.
