From a security standpoint, the metaphor is indeed like another can of diet coke. While browsers are constantly being patched and updated, the same cannot be said for the majority of apps. The benefits of updating a browser are evident but targeting individual apps is difficult to impossible. Many apps are closed source, proprietary, and marketed by companies that have no interest in security. Even those that have such an interest can only spend so much money / manpower on security issues. Considering most of these apps offer nothing new over their browser based equivalents, this argument makes perfect sense. Once money comes into the mix, it simply becomes an argument against paying money for what are essentially useless apps masking security holes.
