I think that kryptonite belongs to Superman like a Ring to Green Lantern. Without Kryptonite, Superman would have abilities like a god, and he'd be practically unstoppable. Of course, there are other weaknesses, magic and the aura of a red sun in the comics, hypnosis or an attack on his super-senses in the series. But kryptonite would lose its value - both in currency and in its value as a plot device - if you could find it everywhere.
If kryptonite was too common, Clark would get into the habit of X-raying his surroundings - especially if crooks are involved - before barging in. If he found kryptonite, which is habitually found in a lead-lined box, he'd seal it first with his heat vision before making an (obvious) appearance.
So, should there be a cure for kryptonite? Well, that depends on the author, I think. If you, as an author, decided that Superman's blood is needed, maybe for enabling Lois to conceive his child (or survive its birth), then there should not be a cure found beforehand, or there wouldn't be a next generation. But even if you don't need Superman's blood for anything in your universe, a cure for kryptonite is not something you should introduce lightly because the mere possibility that there could be a kryptonite encounter does spice up any a-plot.
So, do I enjoy stories where Superman gets hit by kryptonite? I don't think this is a simple yes-or-no question. Some stories are great and only because of the effects of kryptonite, and some have a very vulnerable Clark Kent as a main character. Other stories show just how weird the effects of some varieties of kryptonite can be: We've seen Clark get addicted, aggressive (I think), treat Lois like a pet, be turned into a 'super stud' and so on.
I guess, as with every other plot device, it's not the device that counts, but how the story is written.
