This 'hiding' makes sense with lists of items, each of which has the same options. You wouldn't want to see 30 identical delete icons, it would be ugly. There are two important examples. Twitter hides the actions buttons and facebook doesn't.

Twitter uses icons and media-poor tweets. So having the actions invisible is the best way to go, otherwise the UI will be too cluttered with actions.

Facebook has wider spacing, more graphics in the post itself, and its actions are text-only. That's why they can be visible - they don't distract you from the content.

So I wouldn't say having invisible actions is bad. It's just not always good.