Timboli: What is it about such literary heroes as Tarzan, Conan and Elric, that makes you and I and others prefer the other writings of their authors ... seeing them as better productions?
andysheets1975: Because those are how they made their big money. Whenever ERB needed a cash infusion, he knew he could crank out a new Tarzan book to cover it. Howard wasn't rich, but as a full-time writer who was the primary caregiver for his mom, he knew he could do a "Conan vs. monster" yarn for a guaranteed sale, which was crucial for his circumstances.
That is the simple answer, but there is a lot more to it than that.
For starters, they were great characters, so no problem there.
Secondly, no-one said they had to write less good stories about them.
Thirdly, I know ERB was constantly pressured by publishers to provide more Tarzan, and he often had other manuscripts rejected, without what he thought was due consideration. The publishers were only interested a lot of the time in fast money, and turned a blind eye to anything else. Later on in ERB's career, he did get back to writing good Tarzan stories again.
Fourthly, I don't ever recall reading that specific about Robert E. Howard, and I have read a lot about him over the years. I suspect there is some minor truth to it though, but he did submit all sorts of stories to all sorts of publications. Conan stories are only a small part of what he wrote in that relatively short period of his life. And many Conan stories, when you go back to the original version, are pretty good. The problem was editors making changes. You must remember too, that his father was a doctor, so I doubt there was any financial need for his mother from REH.