No atime is NOT broken!!
The problem is Filesystem Designers not implementing it well.
Rather than whinge about it on LKML (Kernel developers & casual enthusiasts aren't the ppl who find atimes useful) implementing atime's better ought to be the focus of discussion. Ppl think about advanced features like snap-shotting and ignore the basic POSIX requirements.
atime doesn't need synchronous update guarantees, in real use the fuzzy relatime (better 23hr min update than 24, to be predictable on daily jobs) would likely be adequate. If your FS can't stand some inode info updates, during reading, then it is what is broken, not the spec.