Well, can you define what do you mean by “expensive”? How many dollars per camera?
Very often manufacturers save costs something like ten bucks per camera with material expenses like chips and that saving grows through production to something like hundred bukcs. So if you sell 100 000 cameras you save 10 million bucks and bosses are happy.
Can you dig the info of the “firmware chip” model up?
I can find a list price for that chip.
Btw, all dslr cameras and most of cheaper digital still cameras have already updateble firmware, so the limitation isn’t technical or economical.