You are absolutely right!
My "paper-designed" Q30 (i'm ashamed for it's ridiculous but i wanted to see what it would look like in the hand...and it's really pleasing :) ) is a 4" screen with a 1:1 ratio and 7.2cmx7.2cm.
Attachment 218420
Its height is only 12.9cm (and there's certainly a way to do it a little smaller, as i put on top a 2cm space for speaker and...BB logo)
So we could see a Blackberry devices line with rational screen diversity:
for multimedia: Z30 and Z10 (btw what is Z30 ratio? seems a little more than a 4:3?)
1:1 ratio for business: Q5, Q10, Q30.
Still no idea about the definition a 7.2cm squared screen could sport?
There's to say that a 1:1 ratio fits very well with a physical keyboard (no landscape mode) as it always looks a little awkward to turn a 4:3 screen 90� with that keyboard that seems useless in that position.
But i must admit i always loved this concept:
Attachment 218454
Look at that tiny space for the speaker, and no Blackberry logo too!