The thing is, as far as I've gathered, hypersomnia is usually pretty bad, but I hear most people who have it to some degree can be awoken by external means even though their inner physiological mechanisms won't do the job. In a way, mild hypersomnia is much better to have than mild insomnia, because the cure for the former is basically an alarm clock and some coffee, and while one may need more sleep, one might still manage the timing of it. Which is why you don't typically hear much about the ailment in general.
Of course, non-mild hypersomnia is no joke, especially once you you start talking about narcolepsy (which is its own flavor of nasty) or whatever it is that I have.
That said, if I had insomnia to the degree that I have hypersomnia, I probably would be dead or crazy by now, because there's a point where sleep deprivation kills you. So I count my blessings.