Though this also raises the issue of meta-akrasia, wouldn't people learn to not like taking the tablets if they don't enjoy anything they do for the next hour?

I don't think so. This is the same idea as in my melatonin post about making yourself go to sleep; hyperbolic discounting means you can be rational about taking the pill well in advance, even if by the time it kicks in, your preferences have changed to prefer to have not taken the pill.

(And not enjoying things isn't the same as displeasure or pain, after all. People don't particularly enjoy most of what they do - it's the extremes which are unusual & rare.)