You make your points very well and I found your post to be very informative However, the conclusion of your post is unreasonably harsh, for a variety of reasons.
Despite having been around for a long time, it has never really caught on. I had never heard of reactive programming until this particular article appeared, and I've been doing software development for a long time. To me that means it is nowhere near as good in practise, as it sounds in theory. Maybe it was too impractical to implement before now, who knows. But the fact remains that it is up to proponents such as yourself to *demonstrate* the value of this new method and how it is superior to current methods. And based on my moderation score, it's clear that I'm not the only one who is dubious about this new method.
Your accuse me of having a lack of understanding and imagination. I will grant you the former to an extent, but I challenge the latter. I can hand you a clump of mud and say, "You can build a skyscraper with this, if only you had the imagination!". Of course, then you could try building a mud skyscraper only to have it tumble into a pile of mess.
I am one of those people that becomes intensely skeptical, the instant someone starts to go on about how the latest new technological whatchamabob will make our lives easier, increase productivity, cure world hunger, etc., Simply put, I will not waste my own time and energy imagining the possibilities, when you have not yet demonstrated that this new methodology is even fit for purpose. Perfect example: People were falling over themselves about how fantastic Ruby on Rails was. Twitter even wrote their entire backend with it.... Only to have to rewrite their entire backend in Java, because it turned out RoR had very poor scalability.
And now here you are, describing this wonderful new implementation of reactive programming by Microsoft. A proprietary implementation by a company whose name is a synonym for 'ulterior motives'. While this has nothing to do with the technical merits of reactive programming, it goes a long way to getting people interested enough to look at it. I simply don't trust anything that comes out of Microsoft. From stealing work from supposed 'partners', to subverting industry standards bodies, they have a long and well documented history of screwing over *everybody* to get what they want. Even if reactive programming is as good as you say, I absolutely will not trust Microsoft's implementation of it.
But thank you for the brief intro into reactive programming. It does sound interesting, and I will have to do additional research on it to find out more.