I don't think it is that strange. Command line tools such as grep don't appear to be a development priority for Apple. Their focus appears to be on features visible to the average user, who uses the GUI instead of the command line.
Command line tools are mainly used by developers and power users, and the existing tools are generally good enough for most purposes, and people who want something better can always install the GNU versions using Homebrew/MacPorts/etc. There isn't much market demand for improvements in this area, so it makes sense Apple wouldn't invest in it.