This is a good example of why we should be oh so concerned about sales figures. Canon has been behind in low ISO dynamic range throughout their sensor lineup for a few years now, and it hasn't hurt their dSLR sales.
If the roof on your house looks to be in excellent shape and doesn't leak, would you replace it? Unlikely…if it ain't broke, don't fix it. From Canon's perspective, their sensors 'ain't broke'.
I'm from Canada, and even though hockey isn't a favourite of mine I'll use a fact from that world: The Toronto Maple Leafs haven't won a Stanley Cup since 1967. They rarely get into the playoffs. They generally play decent to poorly. (I'm generalizing here, but on average, they are not that great a team).
Some would say, with this data, that the team needs a major overhaul. That alot of money should be spent on improving performance with the aim of bringing the cup back to Toronto.
But then you consider attendance: Leaf games are pretty much ALWAYS sold out. The moment tickets are available they are scooped up and the only tickets left are standing room. Add to this: Leaf tickets are among the most expensive tickets in the whole league.
So, what does this tell us? That despite piss poor performance, they are making a crap load of money. If tickets to their games are really expensive, and yet every game is sold out within minutes of going on sale, where does that leave things?
From their end, what is the motivation to improve? The team is making tons of money. Why should they spend more money to improve if it won't make them more money?
Canon is in a similar position IMHO. Their products mostly rule the market. Their products aren't bad, but they aren't leading edge, yet, they still make a ton of money.
Yes, if they went crazy with the spending and made every facet of their products better then anyone else they'd likely sell more. But if you add up the cost of doing that vs. the additional revenue do you think they'd be ahead?
Canon has a ton of really smart people, and that includes the money side. I GUARANTEE you that the money people have told the big wigs that it's not worth it. Why improve a product beyond the point where it'll make you more money?
Canon as a company isn't stupid. They've for the moment nailed the DSLR game perfectly. They introduce marginal improvements which are minimal in cost to them, just to keep going enough to fuel sales. They have the freedom to focus on areas that traditional DSLR users don't care too much about (live view focusing).
Personally I'm very happy with my Canon gear. While on paper the competition is "better", my personal experience is that it isn't better "enough" to warrant a switch. That's what Canon relies on. That's what Canon is successful with.
The market can change quickly, who's to say if this tactic will continue working much longer. I guess we'll see.