The problem is one of cost.

The only reason why something like Object Desktop can be sold for $49.95 is because it isn't in stores. That savings is passed on to the users.

Let's use WindowBlinds though as one example. We actually did put that in stores once.  The box cost about $3 to manufacture. Getting to to the stores was around $1. The stors required about $2 per unit in "Market development funds".  And the wholesale price had to be $13.50. So on a given sale, we made $7.50.  Of course, that's not counting returns (5%) which were essentially ruined boxes at that point.  Damaged boxes (another 5% of units).

And on top of all that, you have payment issues.

As others mentioned, even today we're still trying to get paid for retail sales of Galactic Civilizations. Not the stores fault, our publisher, Strategy First, filed for bankruptcy owing us hundreds of thousands of dollars.  Only direct sales saved that game. 

So that's why we don't sell desktop enhancements in the stores. It would require us to raise our prices too much. 

Check out Norton Internet Security. It's $70.  The features in that would fit into a couple of Object Desktop (or ThinKDesk) components.  You're paying $70 to subsdize the overhead they have to having so many distribution channels.