IIRC the sub-munition load in JP233 included some that were DESIGNED not to go off on impact (ie mines), to hamper strip repair efforts.
I think the real reason we got shot of them, though, was because they were crap. And risky to deliver.
One can still legally use cluster munitions, as long as one doesn't load any mine-type sub-munitions. The issue with them is the dud rate - if you're dropping 100 bombs in one go, you're likely to get several duds every time.