Comment by pcwalton

Unfortunately, people write microbenchmarks of malloc and free a lot (and not completely without reason: they do quite often show up high in profiles).

For example, binary-trees on the Benchmarks Game is basically malloc/free bound (or at least is supposed to be as Hans Boehm originally designed it). Likewise, most JavaScript benchmarks (V8 splay, for example) are heavily influenced by raw allocation performance. Many people choose browsers and programming languages based on relatively small differences in these results. All of the incentives align in favor of performance, not security, because performance is easy to measure and security is not.