But you're assuming that the only reason to be in business is to generate revenue.
Revenue is a necessary result of operation, not the sole reason to exist. Companies exist because the founders/investors want to achieve something.
I have a bridge in Brooklyn to sell, Peter...
Businesses are meant to create shareholders value. Value could be beyond cash, but as soon as you go public, cash is king. You don't own your business anymore. Millions of shareholders, from institutional to hedge funds to a grand-mother's retirement account, they all demand returns (dividends and/or stock valuation).
In that world, a CEO is forced on a daily basis to make choices that are not necessarily his favorites.
Let me make a statement that may shock you: if the revenue stream is not dependent on R&D investment, R&D investment goes down to zero. And Eric Chan and many other skilled researchers, engineers and developers at Adobe will fire up their resumes and seek jobs with Google (Nik) or somewhere else.
That is, IF (capital IF) revenue is independent from R&D investment.
It isn't so.
However, no one could argue that the revenue stream in a forced rental model is as dependent on new releases as a purchase/upgrade model. Therefore, there is a reason why Adobe needed that: if they can't grow the topline fast, may be they can shrink the expense line, and therefore grow their profit line (bottom line) faster.
The bridge in Brooklyn is for sale, you know... (Just teasing, don't take it too seriously)