The real missing piece is 8BF (Photoshop plugin) compatibility. There is an entire ecosystem of productivity enhancement out there that's missing from the GIMP, at least from the professional photographer's point of view, that, absent a coding pro photographer scratching his own itch, probably isn't going to be filled. Selling a $200 plugin for a $600 program to reduce image turn-around times by an hour apiece works in the pro world; selling a $200 plugin for a free program to people who have essentially all of the time in the world to do things the hard way is a fool's game. That's a sort of chicken-and-egg problem—until there is sufficient pro adoption of the GIMP, the tools won't be there; and until the tools are there, there won't be a large-scale pro adoption of the GIMP. (A wedding photographer, for instance, may have 200–300 images from a wedding that "make the cut" for the album and slideshow, and need editing. Spending even ten minutes per image on skin is a week's work somebody has to do and somebody has to pay for. A plugin that takes that down to two minutes is the difference between profit and failure, even if the big prints still need manual work to look right.)
I disagree. Maybe one in ten of the professional photoshop artists I know use _ANY_ 3rd party plugins. I think the photoshop plugin ecosystem is surprisingly unhealthy for such a dominant platform.
I have tried to convince myself to put out some photoshop plugins, but I just don't see many people buying the plugins already out there.
Also the photoshop plugin API is crufty as hell.
What percentage of plugins out there are being rewarded well by the marketplace? I would bet that there are only a few plugins on the market right now that make a noticeable amount of profit.
It's not only not "in the box", it doesn't support many of the high-end filters/plugins pros depend on (something it has in common with many basic 8BF-compatible programs, like Corel's PaintShop Photo Pro and Topaz Labs' photoFXLab).
