Template engines allow for easy and flexible UI building.
Allows the use of functions as properties to compute properties of objects.
Allows for nesting view templates into top-level views from within a template.
The MIT License is a very permissive license which allows all uses, including business use, without warranty.
Built-in utilities to help validate client input before it gets processed or sent to a server. While this does not replace server-side validation, it can vastly improve the user experience.
Legacy browser support can be important for corporate projects and projects with a large user base consisting of Internet Explorer users.
Plugins offer an easy way to extend the functionality or integrate with other services. A high number of plugins may indicate an active community of users. Only official plugins are taken into account.
This shows that the framework has a living ecosystem, large community support and allows for more flexibility and faster development.
Includes utilities to keep models in sync with their server-side representation without the need of writing jQuery boilerplate ajax calls.
Does not require or seriously encourage the use of a specific library (like jQuery, Zepto or MooTools) to handle DOM manipulation and can be used with one the developer prefers.
Bower is an easy-to-use, npm-like package manager for frontend applications.
Asynchronous Module Definition libraries allow for easy modular, clean programming. If a framework does not work well with such libraries, it might have some other means to modularize its components and resolve dependencies, like Dependency Injection.
Views can be bound to update automatically when an observable object changes.
Models are observed for changes. This is a well known pattern. Can be more performant than dirty-checking in some cases.
Routing allows interaction with the browser url. This is very important for a good user experience if you are building one-page apps.
Has an internal implementation of the Promises/A+ specification. Promises are a popular alternative to callbacks when dealing with server responses.
Smaller file size means faster load times.
Supports a template engine that can be pre-rendered on the server. This possibly improves page speed, especially on devices with low computing power.
Less dependencies means less extra scripts to include, usually resulting in less development overhead and faster load times.