Clearly, the best way to prevent applications you don't want running on your platform is to prevent applications you don't want running on your platform. The p

Clearly, the best way to prevent applications you don't want running on your platform is to prevent applications you don't want running on your platform. The problem comes when the user's opinion of an application they want is different from the platform's opinion. Apple's approach doesn't prevent malware, just limits it to installs by exploit - jailbreakme.com was a very public example of a webkit exploit (I assume) - and there have been plenty of others, including currently active ones. On the other hand, applications that will play by the rules only have the official platform to go through. This means that while malware can and will get through, user desired applications like functional alternate browsers, flash and alternate mp3 stores never will.