Hover effects aren't awful for usability at all. It is about using this in the appropriate context.
They add two distinct advantages:
1) Ease of accessing additional information. Instead of having a click based event a rollout is 100x easier to accomplish and can reduce clutter on a page. This is accomplished by being clear with labels, such as a "More Info" or "Rollover for details". It is surprising to find out out how many users won't click.
2) Whimsy. The emotional impact these have is wonderful, and to discount it is to ignore the delight of this new medium.
As for the touchscreen issue, these would be handled in a click state. This is how hover menus are handled in iOS for example.
They add two distinct advantages: 1) Ease of accessing additional information. Instead of having a click based event a rollout is 100x easier to accomplish and can reduce clutter on a page. This is accomplished by being clear with labels, such as a "More Info" or "Rollover for details". It is surprising to find out out how many users won't click.
2) Whimsy. The emotional impact these have is wonderful, and to discount it is to ignore the delight of this new medium.
As for the touchscreen issue, these would be handled in a click state. This is how hover menus are handled in iOS for example.