So, here's the story:
When Starbucks was just a baby, they had two sizes "short" (8oz) and "tall" (12oz) which I believe were both Italian? Or Italian-based? But since Americans like everything big, they added "grande" (16oz), and then eventually venti (which literally means 20) and trenta (which means 30).
So what sucks is you hear "grande" and think "that's big". This is opposed to somebody like McDonald's, Burger King, or Wendy's, who all just made their cups bigger.
I mean... have you seen a Wendy's medium???