This argument works for me. I feel much more tempted to invest hours in development for a platform where I can control the application access myself if I want to.

However, with all these app stores popping up like mosquito bites on a pale nerd on an involuntary forest hike, I think maybe that freedom can't be taken for granted in the long run. There's a lot of money in controlling the app access. They don't replace software repositories and software pages like http://maemo.org/downloads/ with aPp stores because it's a better service. They replace it because aPple makes a whole bunch on moneyses on theirs.