Well your last example makes the case for why most new customers find the Creative Cloud more attractive than the traditional model, because you'll get several years worth of the latest versions (upgrades included) of more tools for the same price, plus the monthly payments are more affordable than a huge outlay upfront, and you have more flexibility to start and stop as desired.
For existing customers Adobe does offer a first-year upgrade discount on CCM but the comparison math is closer.
Finally, with the Cloud it's not quite "all or nothing," as they do also offer Single-App Memberships for $19.99 a month, which are "a la carte" like you mention for any individual application of your choice (like just Photoshop CS6/CS7).