There’s something satisfying about slimming down an app’s executable file(s) to be as small as possible. It’s not unlike the joy of removing dead code from a codebase; or, to use a non-programming example, the satisfaction of emptying your home of clutter. It feels good to remove clutter, whether that clutter is unneeded lines of code, bloated file sizes, or things in your home that you just don’t need anymore.
TL;DR Dart is worth watching because 1) it can be used to create many different kinds of apps (mobile, desktop, console, front-end web, server-side web, cloud function), 2) it has nice tools that work well on several platforms, 3) it has a strong and growing community, 4) it has a promising future with Flutter rising in popularity and Fuschia coming someday.