Actually, HP does now make a line of printers (the HP Photosmart series), that now have a separate ink cartridge feeding into a separate "heavy-duty" print head. the advantage of those is the printer self-cleans its own heads and it recycles 100% of that ink used for cleaning (where most is wasted) back into it's ink pools for greater output. I don't believe any other manufacture can do claim that. So we have now some of the best "cost per page" we've ever produced.
But to get back to your good reply, it appears the old business model was expensive printer and very cheap inks. Now HP practically gives some printers away and you actually pay for that printer a little bit each time you by ink. Generally from what I have seen is the cheaper the printer you buy the more expensive it will cost you in the long run with inks. But of course HP wants you to buy their ink for that reason. So does Epson and Canon.