For out-of-the-box functionality there should be no excuse for missing descriptions.
The Work Queues:Set Data action (image below) is a perfect example. This is a highly useful function but even if you've been using BP for a while, who knows what it does?
Frankly, it is lazy product development not to have descriptions for standard functions when the facility to display descriptions is right there.
Importantly, they should be useful - not just the obvious "This action sets data in a queue" but detail of how you do it, so someone developing their skills can understand. For example "On Get Next Item this action writes the data in the output Queue Data Collection back to the queue..." or whatever.
Perhaps you provide a facility to crowd source the descriptions and have a panel choose the best?
