They could have been cut back in fall if you had preferred - but may folks like to keep them intact for winter interest and for birds. It is less a case of 'too early' as opposed to 'too late' :-) You want to cut them back before or just as new growth appears. With warm weather, new growth could be prompted to emerge and you want avoid cutting into that to any significant degree.

My prof for our Ornamental Grasses class in hort school drummed into our heads "late February/early March" for cutting back or grooming any type of OG!!

Hmm... The ground is still pretty well frozen if that makes any difference. I just know that I waited too long last year so they didn't really get any bigger. And I don't actually know if that's why, but that's the impression I get from the research I've done.

If the grasses are hardy for your zone, it makes no difference to cut them while the soil is frozen or to wait until it thaws. It is the activity of the grass and when it starts to grow that will determine the timing. And cutting back or not cutting back has no impact on whether the grass will increase in size (spread). Grasses growing wild have no one to cut them back and they will develop properly. Cutting back just improves the appearance in the garden and reduces self seeding on those so inclined.

The Calamagrostis (Karl Foerster, Avalanche) are cool season grasses and will start growing soon so cutting back now before they are in active growth is advised. The flame grass is a warm season grass and won't start growing until temperatures warm up in mid to late spring so you can wait longer for those if you like.

I could not agree more wholeheartedly! I grow Calamagrostis 'Karl Foerster' and 'Avalanche' as well as Miscanthus 'Purpurascens'.

If I did not still have over 2 feet of snow I would be out making sure the Calamagrostis were cut back. It is one of the first plants up in my garden.

I cut back the Miscanthus 'Purpurascens' (but no other Miscanthus) in late fall/early winter after it has been beaten down by a couple of early snows or when it is no longer attractive. It comes up later than Calamagrostis but very early for a Miscanthus. There is little worse than trying to trim an Ornamental grass once growth has begun.