Most programs don't use anywhere near enough cpu to make parallel algorithms pay off. So you may as well keep it simple, especially if you aren't hitting the limits of your current algorithms. Simplicity means less code, which means less bugs.
You don't need parallel algorithms to see the effect of memory ordering bugs. Any program that runs concurrent threads (for different operations, say a thread for computation and a thread for IO) can be affected if the threads attempt to share information. Any sharing among threads must be done very carefully.
