Is it the community behind React, and if it is, what about Google?
This is not about why MDG is behind React. It is more about why people are preferring React.js over other MDL approaches which not only look elegant, but are better in many ways. And Google. You can’t ignore that.
So, if we are getting ready, would it be feasible for startups to spend time build these components/UI elements for their own project using HTML/CSS/JS only to find out later that now every browser has WC support, and that Google already did what they were doing?
I guess it comes down to preferences. Note polymer is not the same as the elements that come with it, it’s just the polyfills and extras on top of the current unfinished webcomponent specs.
I love using Polymer / the custom element library because it gives me security to have a maintained library of elements that work amazingly well across different screen sizes/devices. It’s most likely that for example the React Material UI components would not be maintained properly after a while, while all the components on the Polymer element catalog are officially maintained by Google.
I’ve never used react because it seemed awfully complicated versus Polymer. Why is it not becoming popular? Probably because until recently Polymer just wasn’t production ready. They just launched 1.0 about a month ago. Before that the polyfills were sort of working but they weren’t working 100% perfectly prior to 0.8. 0.5 still required a lot of testing and customization of your CSS code to make sure the styling of the elements was correct (behavior was great though).
I’d say it’s really a matter of building awesome sites and apps with Polymer now to show what you can do with it. I’m not sure about angular/react but Polymer still has quite a big footprint. The site I’m working on right now has about 500KB in size with all the custom elements and the polyfill included. Not exactly a big issue in countries with fast internet but in Asia it’s kind of a big deal. I’m spending lots of time making sure to get my Polymer footprint as low as possible right now for my products’ beta launch.
Wondering about this too.
I have a bit of a crush on Polymer and the Element Library, and React unlike Angular2 seems incompatible.
But Angular doesn’t really seem to gain traction within the meteor community?
So, basically now I’m torn between Meteor/Blaze+Polymer and MeteorReact 
It would actually be interesting to get support from MDG how to use Polymer with Meteor properly. I think Polymer is pretty much at a stage where it’s safe to make it easy to integrate into meteor.
API isn’t really changing too much anymore and I also don’t think that there will be too many new experimental features anymore, rather the ones that are still experimental will be finalized soon. There’s a lot of try and error to figure out how to use Polymer with Meteor the right way. For example right now the polyfills aren’t working for me with meteor for some reason that I haven’t figured out yet. Probably has something to do with load order I guess but an FAQ / best practices would be really nice to have.
Why are you thinking that “Oh, we should paste really cool WebComponents, and then my app would be the coolest and fastest one”? Just take React/Blaze and work!