Yeah, everyone discourages them, even us. Just only use them for that one thing that only they can really do to save Ukrainian lives.
When a cluster munition bursts over a trench system, (or any other really rugged terrain for that matter) some of the smaller submunitions inevitably fall into the trench, significantly reducing its effectiveness as cover from the bombardment. This capability of sudden, wide-area impact cannot be easily replicated.
There aren’t many good “counters” for dug-in infantry. This is one of them, that’s all. It saves Ukrainian lives today. Though if any accidentally unexploded submunitions are not cleaned up with great care, it can come at the cost of innocent Ukrainian lives tomorrow. That’s the only issue.