Mmmh, I woudn't say so. I move the coursor to the left or the right more often than selecting text or make a undo. I use this while writing sms, emails, writing at a web forum or the terminal. Its even faster and more accurate than simply pressing the coursor key and wait until the cursor is somewhere in the near you wanted to have it.

I often use [Ctrl] + [Enter], too. With fat fingers it's possible to press more than a single button at once. But it feels even at the N900 not natural.
You cold be right, the most buttons for Ctrl combinations are on the left. But they are not so often used than the combinations on the right. Don't count the number of combinations. Count the number of times used a combination.

And Nokia decided anyway to remove some Ctrl combinations at the left. At example [Ctrl] + [A] at the File Browser. (introduced with PR1.2)

Yes, thats true. But this is a key without used keycombinations. They were able to place it everywhere at the keyboard. It's only needed to press it with a single finger.