The thing with Elric, is that it's a weird series. He wrote the original series in what, the 60s, which had a definite end. But later on, he went back and wrote more Elric stories (whole novels, actually, the early Elric stuff was sort of short stories/novellas).
I would also disagree that Moorcock's writing style has stayed the same. He varies his style greatly from series to series, depending on the series. And even within Elric it has changed a lot - the very early Elric stuff is written in the vein of Conan (sort of an anti-Conan, but similar prose style), while the later stuff is quite different (since they are whole novels, not just short stories, you don't have to develop things so quickly). In the later novels, I do think Elric's personality becomes far more developed, simply than just being an anti-Conan.