"Just why is it app vendors still predominantly write for iOS first ?"
http://www.developereconomics.com/reports/q1-2014/ : "Android continues to dominate Developer Mindshare with 71% of developers that target mobile platforms developing for Android."
iOS developers may be more loyal to that platform, but that's natural, as the iOS market contains a lot of old Mac developers who hit the big-time when iPhone's App Store opened. Their preference for iOS does not change the fact that it is that Android which is targeted by more developers than any other platform. (For tablets, iOS is still the preferred platform, but not by enough to redress the balance, and we are talking about headphones which are primarily a phone accessory).
The flaw of your argument regarding a new "super headphone" connector is that there is no part of it that requires Apple to acquire a headphone maker. All they'd have to do is bribe/incentivise an existing maker like Beats to produce headphones with your super-duper connector, make some themselves and an sell an exorbitantly priced adaptor for good measure.
Apple don't care about setting a standard. I'd go further and argue that the last thing Apple wants to become is a de-facto standard -- that opens you up to monopoly complaints, and you get sued and eventually have to licence your technologies on a FRAND basis (which usually means not earning much from them).
As I said, though, the days when Apple could move a market like this are now gone - iOS has a good share of a mature market, but it's static; it isn't making any new conquests anymore, and a lot of the companies that invested in the iOS accessory market never made their costs back.
I believe that you live in the USA. This is where Apple's market share is the healthiest in the world (thanks largely to a carrier pricing model which makes iPhones the best value of all options), and it can distort your perception of how the platform is doing overall (Apple has always been strongest in the US: even when Apple was in the shitter in the late 1990s, I remember that we were still selling reasonably well into the US market). The situation in Europe is very different, where fairer pricing has made Android is dominant, and iOS is even outsold by Windows Phone(!) in a few markets, notably Italy.
And regarding the bananas, I'll just assume that you were offering me a nutritious fruit that's rich in potassium, rather than calling me a monkey.