There's a lot of discussion related to server vs client side application rendering. While there is no "one choice fits all" solution, I'll try to argue in favor of client side (specifically AngularJS) from different points of view. First of them is architecture.
Well done architecture has clearly defined separation of concerns (SoS). In most cases minimal high level configuration is:
- Data storage
Each of those layers should have only minimal knowledge of the one above. Services need to know where to store data, API needs to know what services to call and the presentation layer can communicate with the rest only through the API. Important thing to note here is that knowledge about layers below should be non-existent. For example API should not know who or what will consume it. It should have no knowledge of the presentation layer.
A lot more should be said for each of those layers and the situation in the "real world" is much more complicated than this. However, for the rest of the article the important takeaway is that the presentation layer communicates with the server through the API which, in turn, does not know anything about the "world outside". This separation is becoming more important with ever-increasing types of machines and devices (laptop, mobile, tablet, desktop). Back-end should only provide business logic and data.
Taking developers skills into account is an important aspect of the architecture. If, for example, developers are used to work in Java, one should not design a system that is based on C# unless there is a clear advantage to do the change. That does not mean that skills should not be increased with new languages (who said Scala and Clojure?). It's just that productivity of the team must be taken into account and knowledge of programming languages are an important element.
Similar can be said for development of mobile devices. There is no one language fits all. We cannot develop iPhone applications in Java. While HTML can be the solution in some cases, in others one needs to go for "native" development.
The only constant is that, no matter whether it's Web, mobile, desktop or Google glass, they should all communicate with the rest of the system using an API.
Server vs client side rendering
Server rendering is a must for all but small sites. Or is it? AngularJS changed the way we perceive MVC (actually it's model-view-whatever but let's not get sidetracked). It can be done in the client without sacrificing productivity. I'd argue that, in many cases, with AngularJS productivity increases. There are other client side MVCs like BackboneJS and EmberJS. However, as far as my experience goes, nothing beats AngularJS.
AngularJS is not without its problems. Let's go through pros and cons of client vs server-side page rendering. By client side I'm assuming AngularJS. For this comparison, server-side can be anything (Java, C#, etc).
Compatibility with older browsers is hard to accomplish. One would need to render alternative pages on the server. The weight of this argument depends on whether you care for (very) old browsers. The main culprit is Internet Explorer. Version 8 works (somehow) if additional directives are applied. Earlier versions are not supported. Future versions of AngularJS will drop support for Internet Explorer 8. It's up to you to decide whether support for IE8 and earlier is important. If it is, alternative pages need to be served and that will result in additional development time. Depending on the complexity of the application, same problem might exist in non-AngularJS development.
Server performance, if done well (clever usage of JSON, client-side caching, etc), increases. The amount of traffic between client and the server is reduced. Server itself does not need to create page before sending it to the client. It only needs to serve static files and respond to API calls with JSON. The traffic and server workload is reduced.
AngularJS is designed having testing needs in mind. Together with the dependency injection, mocking objects, services and functions it is very easy to write tests (easier than in most other cases I worked with). Both unit and end-to-end tests can be written and run fast.
Google support for Angular is a plus. Having someone like Google behind it makes it more likely that its support and future improvements will continue will full speed.
Once used to AngularJS way of working, development speed increases. Amount of code can be greatly reduced. Elimination of the need to re-compile the back-end code allows us to see changes to the front-end almost immediately.
This view of the client vs server-side rendering should be taken with caution. There is no "one fits all" solution. Depending on needs and solutions employed, many pros and cons listed above are not valid or can be applied to the server-side rendering as well.
It's a brave new world out there. Client-side programming is quite different from what it was before. There are many reasons to at least try it out. Whatever the decision, it should be taken with enough information that can be obtained only through practical experience. Try it out and don't give up on the first obstacle (there will be many). If you choose not to take this route, make it an informed decision.
Client side MVCs like AngularJS are far from perfect. They are relatively young and have a long way to go. Many improvements will come soon and I'm convinced that the future of Web is going in that direction.