For those interested, David and I began this discussion via email. Most communications though, are reflected here as well. Also, we'd love your input!
Remember, your idea of fun isn't necessarily everyone else's! The more options David offers, the greater number of people will enjoy the game. One size does not fit all.
David, no matter the solution, items (or item classes) should have their own cool-down period. Pots, scrolls, etc., at a minimum, should be on their own separate timers. If you're comparing the cool-down mechanics to DDO or something, you've got to remember, with healing, for example, there are multiple mechanisms and, each one has its own cool-down: healing spells; pots; scrolls; items; etc., are all on their own cool-down timer. In EK, the number of choices is greatly reduced, so a categorical, across the board cool-down, is much more detrimental.
My first solution is the simplest. Make the cool-down period different for each difficulty level. For example: Normal - 1 second; Hard - 2 seconds; Iron Man - 3 seconds.
In my second suggestion, cool-down periods can be completely removed and character action delays can be introduced. For example, if, while in the middle of melee a pot is consumed, .25 seconds is added to the next action. In other words, pots could take .25 seconds to consume; scrolls could take .75 to activate; etc. These example numbers are completely arbitrary, by the way!
My third, more complicated solution, involves many different tweaks. For example, after "Using" an item in inventory, close the inventory UI. Users can, of course, simply reopen their inventory screen, but there are inherit delays that would delay actions.
Small cool-downs would still be used with this third method, but the times would be much shorter. Basically, this method would involve a combination of all my other suggestions, as well as other game tweaks. This method would be the hardest to program (and I have many more ideas), but would be much better all around. If this way was chosen, we could kick specifics around a bit and get community input.