You've got several layers of business here: (1) the studio, (2) the production company that funds the studio (the studio might be independent and the production company purchases content from the studio or the studio might be in-house for the production company), (3) the first level of distribution (think "network" like NBC or Comedy Central), (4) the physical distributors (cable companies, satellite companies, streaming companies, wholesalers, retailers, etc.).
It is increasingly the case that all four of these are owned by a single company. For example, TimeWarner owns the studios that make much of the content for the CW network, they fund those studios, they own CW, and they own Time Warner cable and some CW stations that brings the content to your door. And, herein, lies the problem. If you decide to stream a CW show, it does increase the profit at the third level (or at the second level depending on how the contract works) but at the fourth level they are losing revenue _and_ incurring greater costs.
For TimeWarner to "realize there is a ton of money to be made" they have to figure out a way that they make more money _across the board_ and that is a harder problem than first appears. I'm not saying that it can't be done, mind you. But it isn't as simple as saying that _x number of people will pay to stream title y and therefore they will make metric truckloads of money_. For example, say they start streaming all the CW original shows and charging for it. They now have an additional income stream. But this disinclines terrestrial stations from airing that same content so the CW network may lose affiliates that decide other content is more profitable because they won't have to compete with streaming. It also disinclines cable and satellite providers from paying Time Warner to broadcast CW stations. So here are two places where Time Warner as a whole is losing revenue from the decision to stream CW content. Moreover, they lose ratings because they lose marketshare so CW looks less like the young and hip network that it is supposed to look like. And Time Warner cable now has to build out additional capacity because streaming video is taking off.
If this problem could be solved, most content providers would move to streaming in a heartbeat. Why? Because streaming enables what they really want: charging per viewing per device. They really do not like DVD sales at all because they allow for rentals. Their ideal paradigm is that each viewer pay a nominal fee every time that a show is watched. Right now, cable (and satellite) offers the best way to do that with the encrypted digital signals that most cable companies are moving to. Streaming will eventually catch up with the delivery mechanisms of digital cable. Once it does, that will probably be disruptive.