I really can't say how Canon decides what products to bring to market. I imagine it is a rather complex process with far too many "moving parts". I work at a very large, established company that develops online educational platforms. From the outside things look very simple and cohesive, but decision making processes are extremely complex, usually involve hundreds of people, and take a very long time. We have an 80-step process that must be followed to patent anything, that spans at least 7 departments.
Given how large and established Canon is...I'd imagine their decision making processes are fairly similar, at least on the complexity front. Although them being a Japanese company, things are probably more orderly and refined (something the Japanese excel at, where as American companies tend to get mired too deeply into political infighting, empire building, petty squabbling, etc.)
I think that they need to watch out for too many lines cropping up (no pun intended) that makes the buying decision difficult. In the DSLR world, it used to be an easy decision:
xxxD (e.g. 450D, aka Rebel) as the entry level DSLR
1Dx as the professional DSLR
xxD as a little of both worlds
The clear distinctions in terms of price point and functionality made my choice of the 20D very easy.
Now I'm pulling out the precious few hairs that I have left trying to figure out what to get as an upgrade for my aging 20D. I'll never earn a dime with my photos; my preferred subjects are wildlife/birds, but I would love to try landscapes as well. I was thinking 7D for a while, but longing after a 5DIII. I have been holding out hope that the 5DIII would reach a price point where I can mention it to my better half with a straight face. It's starting to get there, but now the 7DII is on the horizon, so I may wait to see what it looks like in terms of specs/price. I keep dragging my feet, and Canon is missing at least one sale (mine) as a result.
[My prediction - I'll buy a 5DIII towards the end of the year unless the 7DII really rocks. I bought my 20D right after the 30D was introduced to take advantage of the price drop.]
Don't get me wrong, it is better for the consumer to have more choices, but with so many options now, I question the ROI on some models. Is the DSLR market really big enough to support so many choices from one company? It's starting to feel like GM of 5-10 years ago.