I assume the price of the EC seat will stay the same or go down. As a DL Gold, I got any number of KLM emails offering to sell me an EC seat which I simply ignored. On the day of the flight I upgraded for free to EC on KLM AMS-YVR. (I was also offered the option to pay 339 euro to upgrade to Business but I went with the freebie.) The woman in the seat next to me was also upgraded for free. Every EC seat on the flight was filled. Be aware that some EC seats are middle seats! I would be very highly upset if I paid extra for a seat and ended up in a middle seat, so it's something perhaps others would want to be aware of. The other lady upgraded next to me was tiny so they didn't fill all the EC seats based on pulling forward persons of height/size as someone else observed on a different flight. I think she had a small status, but her English wasn't clear, other than she said "I was very surprised they allowed me here." She was the last person upgraded and moved into EC. Maybe she was Silver or KLM equivalent? All EC seats were well marked with orange signs.

While I'm not sure why the OP is upset that some people are getting the seats on KLM for free, I will say that he has a point if he was in a row with middle seats and someone got moved into a middle seat next to him that would have otherwise remained empty. Yet I can't really fathom how, in good conscience, any middle seat can be SOLD as a "comfort" seat. There's more to comfort than legroom, and someone sitting next to you on both sides is a pretty major discomfort.

The program may have some bugs but for me, for now, I'm willing to gamble as a DL Gold on picking a free aisle seat and then asking to see if there are any free upgrades to an EC aisle seat on the day of the flight. I find having people all around me fairly intolerable, so having the aisle is of more value that a supposed 4 inches of extra legroom.