We've come a long way, and now we have a series of completed projects! But, taking the time to get these projects out into the world is just as important. Playing the game in the editor is nice and all, but actually getting the game as its own standalone version has a special feel to it that you can't duplicate in the editor.
And once you get the game published, you can just give someone a
.zip file with your game, but you spent quality time on your project and want to give it the respect that it deserves.
People note the polish that you put into your game and the little things, such as an installer, can help to get players into the mood of your project early on and see your game as a professional title.