I think you're totally right about that. But I also get the feeling, he made them for the money. I mean, all three of those series are very short. Not that I mind that he's treading the same ground, since they're all very enjoyable.
The character designs in No Hero are amazing. But it's probably my least favorite in the trilogy. I might have to say Black Summer was my favorite of the three. It's just a very well plotted page turner. He always manages to create some device for these superheroes to exist, thats just really cool, and it allows him to create interesting abilities. Usually, interesting ablities is the last thing I'd care about, seriously. I mean, Superheroes isn't my perfered genre in comics, but Ellis does manage to create fresh characters in a saturated and generally tired genre.
Other Warren Ellis comics can be quite hit or miss. I think, the comic I was most surprised by was Red. Because it was just so mediocre, and standard. I was afraid I must've missed something when I read it. However, I've read enough Warren Ellis to know he's not infallible. I was excited to see him tackles zombies, but Blackgas was a bit disappointing in the end. Doktor Sleepless was pretty good, very reminescent of Transmetropolitan. There's still a ton I haven't read, the most obvious being Planetary. I have the first trade of it, but there's just too many things to read in my pile before I get to it.
Also on a side note, I've read a few Paul Pope comics recently. And god, this man's art is superb.