iPhoto has shortcomings but the library/database is the same as Aperture and I believe Apple is delaying Photos because they DON'T want another FCP X. While I didn't like the Logic X upgrade it ruffled a LOT fewer feathers and I think is a sign that Apple is being a bit more careful about alienating pros while it goes after the lucrative prosumer market.
has for the most part completely alienated the pro and prosumer market, that market segment is gone FOREVER...
I moved to LR two years ago (when it was apparent that Aperture was abandonware) with north of 350gb of raw images (at that time). I now have hundreds of gb more and there is no way I am doing anything but using LR and PS...
My story is not unique and frankly doesn't care. Photos will be for the mass consumer of iDevices and cater to their needs, which is fine. I will stick with the company whose bread and butter is graphical manipulation.
As an aside, it doesn't matter if Photos is an absolute killer app, there is no going back...