They do have a single app subscription.
Even if you will use just PS, you need Bridge at some point for managing images ... and Bridge is now separate in CC.
I think that Adobe wants to use the popularity of PS for other applications (especially for some web applications according to me) ... and creates an illusion by pricing policy for forcing customers to subscribe for all.
Subscriber number may be a success for now, but Adobe hurted the loyalty of some customers who use PS for a long time ...
And, I think that Adobe created a huge number of customers who will escape from Adobe at the first occasion.
In my thoughts, CC model was a great oppurtunity for making new loyal customers in addition to the present ones ... but Adobe choosen the other way.
Adobe may right for now, but the customers are always right in the long run.
My thoughts with limited writing capabilities in English ))
Yes, Bridge is a separate download, but included free with PS.
Can Bridge be downloaded with PS in a single application subscription?
I didn't know this ...
Then, Adobe is more merciful than I think )