Why do some creative people reject opportunities to change directions?
The combination of art and commerce has never got along entirely smoothly. Many creative people working in the entertainment industry are not in a position to control the decisions made about the properties they are employed on. People working on a radio program, television program, comic strip, film or comic book are frequently a hired hand who must temper their sensibilities to what the owners expect or else be out of work.
People who have toiled long within these fields on other people's properties often yearn to seize the means of production for themselves, to leave their former owners and create something wholly original in which they have a larger say in about creative decisions.
When creative people leave a property they were well-known for and move into something else, they don't necessarily continue in the same oeuvre which made them famous. When Dennis Weaver left Gunsmoke, it wasn't so he could star in a different western program; when McLean Stevenson left M*A*S*H his next show wasn't another army/medical comedy; Alex Raymond's post-Flash Gordon work was not science fiction.
But occasionally, creative people leave the property they were best-known for to take on exactly the same type of material they had been doing before. It can pay dividends; when Freeman Gosden and Charles Correll wanted to move their radio program Sam 'n' Henry from local broadcasting to national they couldn't because they didn't own the property; quitting the show, they developed a brand-new program which was basically the exact same thing with different names: Amos 'n' Andy. The latter show lasted 30+ years.
But more commonly, it doesn't work out; another radio show, The Great Gildersleeve was perhaps the first spin-off show (from Fibber McGee and Molly) and certainly established many of the tropes which spin-off programs use to this day. However, star Harold Peary - who had been playing Gildersleeve first on Fibber McGee, then on his own show and in motion pictures - wasn't satisfied with the level of creative input he had (among other things, he wanted more opportunities to sing). Peary left The Great Gildersleeve and launched a new program, Honest Harold; but Honest Harold was basically the exact same program - Peary played the same type of character and even employed some of the same supporting cast members. Meanwhile, Willard Waterman replaced Peary on The Great Gildersleeve and did a fine imitation of Peary; audiences had spent years bonding with the character of The Great Gildersleeve and were loathe to accept an impersonation, even coming from the man who created the original; Honest Harold flopped and Peary never had another hit.
When Image Comics launched in 1992, the founding seven creators played mostly within the same kind of stories they had been producing as hired guns for Marvel Comics (but with graphic violence). As Peter David observed at the time:
So when a creator boldly announces that he’s off to start his or her own line, my presumption and hope is that it’s going to be something new and visionary. It doesn’t have to be highly marketable. Indeed, Marvel and DC’s main flaw is that titles are expected to draw significantly higher sales than an independent would reasonably expect for his piece of the market pie. So “Hard Boiled” doesn’t have to sell like “X-Men.” No one expects it to.
If Todd said, “I’ve been dying to do a good romance comic,” I’d be thrilled. If Erik said, “My life’s goal is to produce a solid western,” I’d be impressed.
So what’s Image publishing?
Young superheroes. SWAT Team superheroes. Young freelance superheroes. A group of superheroes.
I mean…haven’t we got Marvel and DC for that? Why have X-Force clones when we’ve got X-Force?
Indeed, Rob Liefeld's Youngblood was made up of characters he had originally created as unused redesigns for titles like Legion of Super-Heroes and Teen Titans. Violence aside, there was very little different between X-Force and Youngblood, aside from fan investment in existing characters and publishing identities.
Sticking with similar type of material leads to creative people being typecast; when Johnny Weismuller left the Tarzan films to be Jungle Jim, he merely left one type of jungle hero films for another. Basil Rathbone suffered from being typecast as the detective hero Sherlock Holmes in film and radio; he finally abandoned the role to take on the part of... detective Basil Rathbone in the radio series Tales of Fatima, doing absolutely nothing to halt his typecasting.
For contrast, look to Jack Webb, who started in radio with the serious news-commentary program One Out of Seven, then the very-burlesque humour of The Jack Webb Show. For a time he settled into programs where he played wry private detectives - Jeff Regan, Pat Novak, Johnny Modero - but broke out of those parts with his show Dragnet, a successful attempt at a grounded police drama. Even with the fame of Dragnet, he didn't simply branch out into other kinds of cop dramas - his other big passion project was the jazz/crime series Pete Kelly's Blues.
I had some understanding of this when I worked at Marvel - I didn't want to be known just as an Official Handbook of the Marvel Universe guy, so I jumped at the chance to write introductory text in Untold Tales of the New Universe, to write the trade dress for trade paperbacks and step outside my comfort zone for properties like Anita Blake and Image's Proof. If you intend to be considered a creative person, you can't simply toil at the same kind of thing from project to project - not if you want to be considered vital. Do the same thing for too long and people will assume that... well, that's all you've got to offer.