Don’t get me wrong. I think there where places where JavaScript, SPAs and so on where the right decision but we used the same tech all over the place. I think that is the negative impact of working in a future oriented industry and one of the reasons you might want some older people in your team to prevent new projects to be started on new tech JUST because it is cool now.
But even within the JavaScript community and the tech there I sort of like Ember.js and it grew out of the Ruby and Rails community. It is not perfect but it fits SPAs perfectly and there is integration into Rails that makes the data handling less tedious (still need to try because unfortunately I got none ember projects + rails or ember + node.js).
If I take my none Ruby and none Rails experiences of the last years I have to say I trust tech that comes from Ruby and Rails guys in other techs more. You can accuse me of Ruby chauvinism but I do believe that we as a community where better able to foster good taste in technology solutions.