Hang on... why does it have to be so complicated?
Why did Apple create Aperture? Maybe it was the hoards of professional photographers (core Apple users) complaining about crappy imaging apps and hugely inefficient workflows.
Can't Aperture just be an app that elegantly addresses serious workflow issues for advanced photographers? Oh, yeah... that's pretty boring for an app to be practical rather than the seed for some great speculation about Apple product development...
I take it you don't do much digital photography with RAW formats? Prior to Aperture, there was one app on the market that offered a well thought out RAW workflow: Phase One's Capture One Pro. But it's such a niche product because all it really does (and does well) is RAW conversion. With the boom in digital photography and the huge numbers of people moving from point and shoots to digital SLRs, it's only logical that many will be experimenting with RAW formats. And even though pros have been working with RAW for years, they've been frustrated with the painful workflow RAW conversion apps have offered. But RAW conversion is only one aspect of the digital imaging workflow black hole.... There's also the (not so) small matter of image management - being able to store and find specific photos years down the road. Who wants to use another expensive app just for that step? So Apple takes advantage of features like Core Image and Spotlight and steps in with Aperture, an app that actually addresses the frustrations of professional digital photographers. It makes editing easy, keywording easy, RAW conversion easy and archiving your huge image library - easy. What other app does that? (oh, yeah... Lightroom, I guess).
Aperture offers simplification of the imaging process. Photoshop offers complex, specialized solutions for those who need and know how to use it. Aperture attempts to be a one stop digital imaging solution (edit, convert/enhance, archive). Photoshop is a piece of the digital imaging process.
Just a second... is it possible that Aperture is already a Photoshop replacement? But I'll let you in on a little secret - so are most RAW conversion apps. A photographer who is able to consistently create technically sound RAW images and convert them in (insert name of your favorite RAW converter), has for the most part a finished product at that point... no real need to go to Photoshop.
My guess is you'll see Apple add functions to Aperture to make it more complete for 95% of the things normally done to images in Photoshop... but the need for an image editing suite? I'm not convinced about that.
Is Apple Building A Photoshop Replacement?