With browsers and sites like GitHub moving to even shorter release cycles, I can't see what advantage a longer release cycle (such as twice per year) for WordPress would achieve.

The feature plugin approach means development can be done irrespective of the release cycle. The fact that some feel that these feature plugins aren't "wow" is a different issue to the release cycle.

It is an old platform, and while it may not have some things folks would consider to be basic (i.e. SEO), it's not necessarily advantageous to have that in core - if Google and friends announce a big change, just after a WP release, then either everyone is getting it wrong for the next 4 or 6 months, or a plugin is needed to fix things in the meantime. Plugins, naturally, have a shorter reaction time to external influences.

Personally, I don't need "wow". "Wow" means shiny and new, and more often than not, new bugs. As of just now, there are 1956 bugs (of 3767) listed on Trac that I'd rather see addressed long before any significant new features are added. I'm also loving the work to objectify existing code (though there are some questionable OOP decisions). Stability in WP core allows plugins to provide the actual features I need.

I'd love to see alternative releases that purely focused on fixing bugs, like Nacin did for one release a few years ago, until those numbers are reduced to below a threshold - that would set a user expectation so misguided folks don't expect a visual or functionality "wow" on every release.