I think you are referring to diversity, not obscurity. Diversity does indeed increase the resilience of the network, but there will always be enough common factors across the board, that diversity alone will not suffice.
In the end, the software that we depend on, must be reviewable by anyone who is concerned about it. A prerequisite for that, is that software should be as small, clean, and simple as possible, to encourage such scrutiny. IIRC, the real problem with heartbleed, is that the OpenSSL codebase was a mess, and no-one wanted to work on it.
That's my point, as I type this on fully patched Win 10 Pro.
Certainly Windows has its issues, but it's biggest 'flaw' when it comes to malware isn't that it's closed-source, but that it's ubiquitous and therefore a highly attractive target.
Linux is ubiquitous in the data center. We are not a low-value target. Also, corporations with cloud-based infrastructure are more likely to pay large ransoms for their data, especially if it is the backup/archive system that is attacked.
Data centers are dwarfed in size by the consumer and business markets, while also being much less vulnerable due to their more specialised nature and therefore ease of update. Case in point: there are plenty of windows data centres out there, but its not likely any of them were effected by this incident.
In the end, the software that we depend on, must be reviewable by anyone who is concerned about it. A prerequisite for that, is that software should be as small, clean, and simple as possible, to encourage such scrutiny. IIRC, the real problem with heartbleed, is that the OpenSSL codebase was a mess, and no-one wanted to work on it.