If you are looking for a definitive proof of market share vs. security control effectiveness as the primary reason for a cause of hacking successes, I believe you are looking for something that is impossible to prove. The complexity of the question is too big for a single detailed proof for all cases, and in most cases, the data we can gather shows a correlation but not a causation. Add to it the unknown factor - any survey will only be able to consider the reported exploits - undiscovered or unreported attacks or exploits won't be known by the researcher, so won't be in the report.
There has certainly been a correlation between a product's growth in market share and the number of discovered successful exploits against it. It's not the same growth curve for every product, but one way this could be researched would be the growth in published vulnerabilities by a group like US-CERT for a given product. That's a pretty researchable trend with the common theory being that more market share --> more good targets to hack -> more hackers & hacking -> more exploits.
But what you are asking for is "causation" - from market share or poor security design to proliferation of successful exploits. While you may find a study that claims to have proved it, I'd be very wary as causation is pretty hard to demonstrate outside of a contrived test environment, and contriving the test for this would be pretty difficult (I'd love to be proved wrong...).
I will say that common research is showing a shift in the nature of hackers in the current time frame. When I started in security, hacking for the fun of it was a pretty significant force, and a major way of finding exploits. Those were the innovators, and "script kiddies" followed up with reusing found exploits for malicious purposes. So there was a reason to believe that if a product was big "enough" and interesting "enough", some smart people would come along and try to exploit it.
I'd say that today the field is different - major communities of hackers share hacks the way open source developers share code, and high end institutions worry about equally high end hackers who make serious strategic choices based on driving objectives that have nothing to do with either market share or weak security - and everything to do with politics, money and criminal activity.
in all cases, what hackers choose to hack is a choice based on the internal motivation of the hacker, not either of the two vectors you mention and that's going to be caused by larger social forces.
I'd offer that the difference between the two cases you're talking about has a lot to do with the nature of the hacker population. Different hacker communities are motivated by different drives. Some hack because it's fun, some hack because they want financial benefits for minimal work, some hack because they have a non-monetary sociological goal (a group protesting something, international cyberwar, etc). In all these cases, the hacker or group in question is going to choose a nexus of simplicity to hack and market share to fit their specific needs.