You might want to use a browser extension for a few different reasons:
- To integrate with other services you use. For example, Evernote offers an extension that allows you to easily clip websites and save them to your Evernote account.
- To add additional features to your browser. For example, the JoinTabs extension for Chrome gives you a button you can click to combine all your Chrome tabs from multiple windows into a single window.
- To modify websites as they appear on your computer — adding, removing, or modifying content. For example, the InvisibleHand extension adds information to shopping websites, informing you if there’s a cheaper price available on a competing retailer’s website.
Extensions can do many other things. They’re like any other piece of software, although browsers place some limits on what they can do. If you want to integrate your browser with a service or get an additional feature, there’s a good chance you can do it with a browser extension that already exists.
Here's the thing. Can they get the Chrome and FF developers to move their extensions to Edge. It sounds relatively easy, but it will be up to the development community to decide what they want to do. It might seem like an easy decision, but the developer has to support every platform they develop on. I think you won't see a massive rush of extensions in the public at large. At least until folks feel like Microsoft isn't going to pull another 180 in two years. (There's a reason win32 apps are still being developed and universal apps are extremely slow to catch on.)
An RSS Feed extension that emulates the built-in Internet Explorer RSS Feed reader would make my day.