My Pink ID card has great value. First, for entertainment purposes as I always make sure to ask for a discount when I see double-pricing, and then I get laughed at with a negative answer 99% of the time. I did get a foreigner child price once though :).
More seriously, I can use it as a replacement for my passport for most use cases. I traveled for two months around Thailand outside of my province last year and did not use my passport once during that time. It appears hotels don't do a TM30 report when using the pink card as my 90-day report went through (in CNX) without having to do a TM30 upon return.