Adobe Illustrator is a powerful illustration program that I have used for technical illustration for a long time, but some things just drive me crazy. I'm tempted to learn Corel Draw since it seems better suited for technical illustration.
There's no way to zoom out to see everything you've drawn. You can zoom to see the whole page, but you need to manually set the page. At least in CS4 you can do this graphically, through a buried menu, but why not have a Home key that zooms “To fit”.
It is impossible to set any key to subscript or superscript text. Trust me, it's impossible.
Every time you export PNG, the file thinks its modified, forcing you to save it again. You can make a command shortcut to do this save PNG, save again, but it takes you about 20 minutes to figure out how to make this shortcut, and you have to bind it to an F# key. Lame.
The measure tool stinks - for crying out loud, what kind of measure tool doesn't snap to objects you've drawn?
I hate the selection tool, since you cannot get it to select only what it encloses. Anything the rectangle touches gets selected! What kind of moronic selection logic is this? You can use the lasso but why can't you change selection to MBB?
How do you find tools that are mentioned in the help? E.g. the Crop Area Tool? Where the hell is it? Spent 15 minutes on this once. Why don't they build a better help system that is context sensitive. Since Adobe went to web help, it takes even longer to find things. (I finally figured out that the Crop Area Tool is actually called the Artboard Tool.)