Its cheaper for the company to make improvements in steps. The exact opposite of your argument is true. Its far more profitable to reuse 80% while upgrading 20% and it gives previous purchasers an upgrade path. If the new printer is drastically better, I wont mind as long as I can purchase the upgrade parts.
If the new printer is a different class (larger, smaller or multi head) I also wont mind. Ill buy one. A completely new and better version of the x1c thats not interchangeable with the x1c and has a better ams would suck a bit. lol. Maybe not for people that arent invested yet.
Your argument is more based on patents. I understand that part. Open source is best until a product is polished, like printers are becoming. No real reason to open source at this point.