One of my favourite iOS game - “Stair Dismount” has a sequel now. The developer Secret Exit was one of the first iOS game developer with its own impressive engine (Zen Bound had specular lighting, soft shadow) but now they have move to Unity! 
Wow, suddenly it seems just about everyone is using Unity. It should be a good thing but somehow it feels less exclusive 
. It always goes like this.
Exclusivity at a night club is a good thing; exclusivity for a development platform? Not so much.
I know that feeling. I bought Unity Indie back in late 2008, but the exclusive feeling ended when it became free. The great thing about the loss of exclusivity is that there are now more customers and people buying licenses thanks to Unity Free, and the increased income helps UT hire more developers to bring new and better features.
The asset store case and point , not everyone has the time to make everything from scratch . The idea that I can spend 500$ or so and get most of the basic stuff out of the way .
Like who really wants to spend weeks on a GUI system( yeah NGUI takes tweaking , but your saving time !)
And you get to say that you used it before it became popular!
I started with 2.5. But who cares…
It’s a good thing if Unity get’s that popular. That means bigger community, more tutorials, more assets, more jobs.
And for the end user, it doesn’t make a big difference which engine is under the hood, as long as the game is good.
If you want exclusivity, you should code your own engine 