It's a matter of preferences. Some people like writing their own adventures, some don't. There's no reason to pull the "no time" excuse unless you're really pulling three shifts a day or something, but then I'd doubt you would feel like spending so many hours on a P&P evening. If writing your own campaigns isn't high enough on your list of priorities because you'd rather do something else, that's completely okay and up to you - no reason to get defensive, and no reason for anyone to blame you for it.
I will say that dependence on official adventures is an issue in just about any RPG system, though. Few P&P lines publish a selection of ready-made adventures at all, and even of those that do it's just a matter of time until you're through with them, at least if you play regularly. Ultimately, it's always easier/faster to blast through content than creating it, be it a novel series, a TV show, a computer game … or, well, a pen&paper RPG. Accepting fan-made material helps, but even there I doubt that it's enough (as exemplified by your own statement).
Myself, I see official adventures as a stepping stone for new GMs, something to help them find their bearings in the game and the setting - but there's something to be said about that shift to homemade campaigns, tailored to the individual characters' roles and backgrounds. Typically, such campaigns also offer much more liberty to the players as the GM may be more willing to improvise, given that he or she already created the material from scratch anyways and thus feels right at home adapting to the group, whereas official adventures often lead to a degree of railroading to get to page X, as if it's a matter of reaching the next level in a railshooter. Or that has been my personal experience, at least. *shrug*
Have you considered passing the torch to one of your players? Usually, that's sadly a no-go as few people are willing to GM (the greater responsibility involved may be frightening, especially if it's a system as complicated/complex as DH!), but it may be worth a shot.