When you start to bolt on features for dynamism in HTML you end up with Angular. The reason that it has all of those complex features is because it needs them to build real world apps. I'm sure once people have built more stuff with Polymer you'll start to see similar "feature creep".
I've worked with a number of very complex Polymer applications, probably the most complex Polymer applications in existence right now, and the template features have been sufficient so far, and there's always the fallback to code if necessary.
I can think of very few common feature requests (mostly on Shadow DOM, actually), and they don't being to approach the complexity of Angular, which concerns itself with so much more than templating. Angular's complexity is not simply an unavoidable consequence of being used for real world apps - it's just complex.
When you start to bolt on features for dynamism in HTML you end up with Angular. The reason that it has all of those complex features is because it needs them to build real world apps. I'm sure once people have built more stuff with Polymer you'll start to see similar "feature creep".