Cutting back will make it shorter but not less dense or congested. Instead of cutting to the ground, you could try dividing. Dig each clump up, roots included, cut into three to six smaller clumps. Replant one and give the others away.

I was really thinking of visual congestion with all the dead foliage from last year. The clumps are still fairly small, but I'd like less brown and more green. I guess the brown parts are more natural, but I was just considering my options. I didn't want to trim it now if drastic pruning this time of year might hurt the plant.