There's actually a fairly large sweet spot where the sub makes a lot of sense (ignoring the fact that subscriptions inherently suck, of course). If you print infrequently enough that your cartridges are likely to dry out, it's generally quite a bit cheaper.
Of course the correct answer for most people is to just buy a laser printer and go to CVS or something the couple timed you need photo quality prints. Don't have to worry about toner drying out