Major platform Pluggins like Sonos, Hue, Alexa and Homekit etc would be part of the central Indigo platform and not depending on individual developers
Would it be better to make it more open with a (selected) group of developers to create the above. The community is fantastic and has a lot of dedication so why not take that advantage.
I have a question around this -- what makes you feel this way regarding the plugins needing to be included with the core product versus as being downloadable plugins from the Plugin Store? Based upon the forum messages most don't feel this way, but I am sure you are not alone in this sentiment, so I'm curious why? A few of my personal thoughts...
The plugin architecture, especially with nearly all being open source and on GitHub, as Matt mentioned, essentially makes the plugins an open source component of Indigo... this is not that far off of the other products and methods you mentioned. As a developer, this is FAR safer than if, say, Indigo were open (or partially open) because it is more sand boxed; that is, we can feel more confident in only needing to test OUR code, not worry about regression testing parts of Indigo that we might accidentally affect if we were in the main product.
The only thing I can think of that is "somewhat" negative is the fact that you don't have a "guarantee" of support since it came as a developer or community based plugin. But this is true of any open source product. When I first got into Indigo I admit that I had an inkling of that, though over the past few years I have seen the community take over abandoned or otherwise under-supported plugins and they continue to evolve without the original author. I have not heard of many that were every completely abandoned, save those that may have outlived their usefulness.
That isn't to say that I don't sometimes avoid plugins from developers whose code I don't fully "trust" - not from a do harm perspective, but more from a "is it stable/well designed". What that generally means is you might not install the plugin first version(s) until issues are ironed out, where as a first-party plugin probably elicits immediate trust. The technologies you listed, however, have plugins that are pretty robust.
I am not sitting here trying to argue with you by any means, just laying out my viewpoint and hope to get an understanding of where your viewpoint comes from. As an Indigo user and plugin developer, I am truly interested.
Adam