Mercurius
Legend
I think you misunderstand me. I think its great. Sometimes enjoying your own creative passion is its own reward.
I got it. I was mainly joking, although the phrase "mental masturbation" has a pejorative connotation. My view is that creativity is its own reward.
The only problem, as far as RPGs are concerned--and it is a relatively common issue--is when creative world-building DMs inundate casual players with too much exposition. It isn't unlike the issue many (especially fantasy) novelists face with excessive exposition. I think the key is simply to develop a sense of finesse; sometimes less is more. Implying a deep history is often more intriguing than explaining it in intricate detail. "Terra Incognita" is more mysterious than minute detail of every square inch of a map.