the technology was certified and frozen in the 90s. many of these devices are running windows 3.1 for networking!
they cost more than 2 million dollars a piece to install (at least around here) and require 4 trips per year to calibrate.
since there was little incentive and herculean constraints for the team in charge of METARs to improve the situation, another team at the FAA decided to create their own non certified version. to be installed in places that can't afford a METAR. They were able to build a better system using the same hardware but updated software for a hardware cost of $80k, 250k installed. this system only needs calibration once every 2 years. so it represents about a 1/10 cost of install and 1/8 cost of maintenance.
naturally this pissed off some people. I'm not going to get into internal politics beyond saying the project is currently frozen until a number of large efforts imposed on the program are completed. I believe it will still eventually come out because the cat is out of the bag and there are many groups desperate for a better alternative.