The security chips are getting more and more sophisticated as people start to crack the early versions. The R&D cost of this is pretty large, and so is the material costs.
You are only considering HP firmware update. But even in that there will be a huge cost for implementing, testing and deploying this new functionality.
The cat and mouse game of "cracking" the toner/ink chips has gone on as long as they have existed. It's been over a decade since I worked for Xerox on these kinds of chips, so they may have gotten much more complex and expensive since then, but it was always quite a delicate game internally as to what kinds of technology we would actually deploy as it's a very delicate balance from a legal standpoint.
Lexmark has historically always taken things too far on the legal side and really ruined the ability for printer companies to "protect" their toner/ink sales from 3rd parties. One recent way Lexmark has taken this too far is: https://www.supremecourt.gov/opinions/16pdf/15-1189_ebfj.pdf
That's not the first time Lexmark has ended up in front of the US Supreme Court for similar shenanigans. I don't believe they've ever had good luck when cases have made it to higher courts.
The father of a childhood friend of mine was chief counsel during a previous Lexmark supreme court visit (the Static Controls case, I think?). He liked to paint and his basement was full of self-made art, copies of famous works and his own originals. I got the impression he didn't really believe in the corporate position on ink and toner DRM. That may be part of why he retired young.
Static Control Components was always fun to watch! They really seemed like the leader in terms of making 3rd party consumables chips, at least on the tech and legal side of things.
The chips on toner/ink started because there was a need to comprehend how much ink/toner was left in a cartridge and to make sure the right one was inserted. You could weigh the cartridge but that's quite expensive. It's much cheaper to count pixels or ink drops (and their size) and then write how many of those had been used up into a chip on the toner/ink. That way the printer always knows approximately how much ink/toner is left in the cartridge.
Clearly once you have a chip on the consumable, it's natural for a business to consider how this can be leveraged for financial gain. Lexmark was always VERY aggressive about this. When I was at Xerox we seemed to be much less aggressive in how we implemented restrictions.
I have an abandoned patent application from my time at Xerox for restricting a toner bottle to a specific customer. As far as I know, they never implemented it, but we did have the technical ability to do so if we had wished. The downside to an implementation like this is it kills the 2nd hand/resale market, which may or may not be legal. You cannot patent something illegal. I'm not sure if that's why the patent got abandoned or not.
You are only considering HP firmware update. But even in that there will be a huge cost for implementing, testing and deploying this new functionality.