LOL! Nice Q! Here in our Ivory Tower of higher learning where all the grammar rules come from, we just sit around all day thinking of ways we can really stick it to international students of English.

It's not the opposite of "long words". An abbreviation is not a "short word". "Abbreviate" means "to make brief". So the word is written shorter, but if I see "abbr." I will still say "abbreviation". :)

Hi... You're right... It is one of these mystery of languages...

for the same reason why 'big' is such a small word.......

Excellent question. Well agree with Peachey, you need to know the 'nature' of the abbreviations - actually most of them are longer than most single words or are short for some quite long words. Haha you are trying to make fun, I know it.