Clearly the team doesn’t really care about making hover hints to be a learning tool.

Rarely these actually try to say what an option or a field does or controls: like 'Start editing similar shapes together' for the 'Global Edit' button in the Control panel, or 'Click to pick arrowhead to apply to start point of path' in Stroke panel...

But in most cases the hint is extremely rudimentary.
Try to hover the 'W' field in Transform panel — you’d get 'W value'. W?! Weight? Wand? Why not say 'Width Value', or even 'Set Width for the selected objects'?

Then again — why do you caption only icons, but not something like menu commands? Why can’t a new user hover over Select > Start Global Edit and get a short explanation (especially with rich tooltips enabled)?

Why Scale Corners in Transform has a decent hint, but Scale Strokes & Effects — none at all?

Why can’t you make hover hints have several lines of text, if needed?
Take a look at how a carefully written hint for a plugin option suffers from being restricted to one line?

OK, if you’re afraid of flashing with large cards (the main reason why people hate rich tooltips) — why can’t you make these hints display a shorter version, but give a detailed one after a pause, like the attached GIF shows (from a 3DS Max)? Two second delay is a bit too large, to my taste, but it’s there!

Why can’t every item in Preferences have a hover hint?
Actually I requested this here: http://illustrator.uservoice.com/forums/333657/suggestions/46268617

I hope someone in the team just takes time to hover all the UI items in Ai and think a bit. Or scroll through a list you probably can generate... do something, please!