“upgrading from CS4 to CS6 [...] A few hundred dollars every few years”
As you use Photoshop, Illustrator, and AfterEffects, that means you probably have the Production Premium or Master Collection bundle. Upgrades for those bundles did not come cheap.
Adobe releases a new major version of CS every year, and has done so since CS3. CS4 is 5 years old. If Adobe kept its perpetual upgrade plans, you would have to first upgrade to CS6 to be able to upgrade to this year’s version (‘CS7’) – having to buy two upgrades would’ve cost way more than $700. Instead, Adobe gives users of CS3 or newer a discount to Creative Cloud, all Adobe apps for $30 a month.