Ohhh yes, I am in total agreement with you on this, Thor! (As I think my user name and fanfic should suggest.)
I even remember going all the way back to "The Wounded," the first time I EVER saw any Cardassians...I was a little kid at the time, but I remember being surprised at the depth in those three characters, right from the start. Macet, Daro, and Telle had three totally distinct personalities: Macet caught between a rock and a hard place, and having to play politics with both Picard and Central Command to keep a war from blowing up (not to mention his understandable frustration with Picard's distrustfulness and reticence to ACT...oh, and the dumb-as-hell borderline-racist comment Picard made at the end about Cardassians not understanding loyalty--when in fact MACET WAS RIGHT), Telle who's just a typical thug...and then Daro, who really seemed to have a LOT going on under the surface and with whom I could sympathize almost immediately. I mean, I had the feeling that he would've said something really amazing had O'Brien not blown him off--and when that happened...the haunted look on his face just said it all.
My immediate thought, besides being amazed at the way these three characters were acted, was amazing. Minus Telle, these guys had DEPTH. They had restraint (yeah, I know Macet started out guns-blazing, but he wasn't so stuck on himself and some sort of stubborn warrior pride that he couldn't listen when Picard made his case). They were capable of regretting their actions. In that, it was immediately obvious this was going to be more than an alien-of-the-week race, and they were immediately leaps and bounds above the TNG Klingons, in terms of interest for me.
And I think since we got three different "Cardassian templates" right from the start, the race as a whole ended up being developed along those lines. While there were a lot of Telle-like thugs, to be sure, I think this set the tone right away for how the Cardassians would be written in the future.
The Klingons just struck me as flat--one-dimensional, and quite frankly, not played in a very intelligent manner, ruled by bloodlust. Why on Earth the Federation would actually ALLY with them and condone their actions (and not simply have an armistice) is still to this day beyond me.
And it was even more irritating, to me, when Jadzia got into their culture. I was much more able to understand Bashir wanting to find out about Cardassian culture. Me--I think I would enjoy reading enigma tales...much better than Klingon opera, which is probably a cross between Wagner and the Texas Chainsaw Massacre...