The fact that YOU think I need MY desktop 'cleaned up' or I can't keep it organized is pretty damned infuriating and condescending, quite frankly.
I don't personally care what your desktop looks like or how many icons you have on it, or if you're able or not able to keep track of them; but icons on your desktop has little-to-nothing to do with offering a unified launcher platform. You can have the Battle.net app create a desktop icon for each game still, if that's what you want to click on.
Right now each of our games is started through a launcher. The launchers help ensure games are up to date, offer functionality to launch other versions (beta/PTR/etc.), has some file management tools (repair), provide quick links to helpful resources (support), and helps bring info front and center when starting a game like patch notes, game info, news, etc.
Instead of having separate launchers for each game, which are individually updated and maintained, and each of which also likely having different requirements and specifics for how it works and operates, it makes a lot of sense for us to have a single platform (e.g. launcher) that brings all the games together under a single roof, streamlines our platforms, and provides a single launcher--instead of many of them--to provide the same features those launchers always have, plus more, and additional flexibility to add features into the future.
If you're launching Blizzard games now, it's quite likely you're seeing a launcher, and that's not really any different than seeing the Battle.net desktop app "launcher".