Another problem is that, as you know, some of the RC mystics went a little too far in their ecstatic descriptions of things (e.g. Catherine of Sienna). Many of the mystics lived during a time when people began to change the way they understood themselves and spirituality in general.
To put it short, these changes made people value inner visions, inner experiences, and made them understand terms like "inner life" differently. I believe that some of these changes were unhelpful and leading away from truth, and why I'm skeptical of prayer practices where you're supposed to conjure mental images, etc.
However, people are far too critical of these RC mystics. Teresa of Avila, for example, has great stuff. And because we're modern people, we're going to tend to read all of the Fathers in the terms of very different understandings of ourselves and our inner lives than the Fathers had. So we have to fight that battle against error either way, ignoring RC mystics isn't going to help.
Same thing with the Sacred Heart, I think. It falls under the same overreaching condemnations as the RC mystics.