I find the hassle of having multiple game launchers installed to be pretty insignificant. In exchange, developers have more freedom regarding where they're willing to publish, and have the opportunity of exclusive deals that bring in more money and could reasonably be put back into the content of a game.

Also, as players we occasionally get games at much lower costs than normal (sometimes even free), which seems to be a benefit we wouldn't get to the same extent if multiple storefronts weren't competing.