That's the only explanation to the whole set of stupid decisions they've been taking lately (reader, yt UI, gmail compose, ...): they make more cash by doing so.
I'm usually flamed or attacked for suggesting it in most forums, so it's very nice to see people experiencing the same thing with Google
Hangouts is the perfect example. Instead of an easily sortable, easily curatable list of contacts with an easy way to see if they're available or not... now the whole product is shiny, with flashy animations, very little user control of any part of the software, and a whole bunch of Google's "we know best" design ideas like a "special mix" of "recent*" contacts that you cannot alter in any way without actually removing a contact from Google entirely.
I personally think Google held itself back from OTT monetization strategies all these years as it waited for (a) its individual products to become undisputed market leaders, and (b) a unified privacy/social glue across all its products.
Now that the majority of users are locked in to Google - to specific products and across their entire suite of products - they are lifting their self-imposed restraints on privacy/aesthetics/advertising.