No. In fact, the incentive for attackers is exactly the inverse of what you claim it is. The author of WinAPI malware can expect multiple tens of conversions for every one obtained by Mac malware. That's because, breathless accounts in the media aside, malware infections don't compete in any practical sense. You would need to deliberately eschew all financial incentives to target OSX. The logic here is exactly the same and exactly as simple as Joel Spolsky's article about investing in OSX dev from 2002.
As for the rest of your comment: both Windows and OS X are conventional monolithic operating systems written in C with core facilities designed and built in the '90s. Both are multiuser operating systems repurposed for single-user deployments. Both have strong kernel/userland barriers with well-defined interfaces. In fact, if you've done systems programming on both, they simply aren't all that different, even to a software developer.
But: for the past 10 years, Microsoft has been getting hammered by attackers, and has the benefit of a decade-long trial by fire. So when Microsoft randomizes library offsets, they don't (for instance) miss the entire runtime loading subsystem.
Also: most of Microsoft's most sensitive application code is written in C for WinAPI on x86, which is one of the best-understood application runtimes in the world. Much of OS X runs on cross-platform Objective C, which has received nowhere nearly as much research. Put simply: nobody knows how to write exploit countermeasures for OS X. I think mostly because nobody cares.
(Again: I say this as a Unix dev from '93 at a company standardized on Macs).