(1) The App Store has no upgrade path. All purchases are one time purchases. If you release a new version (not an update), it'll must be another purchase. This is how Logic X operates. Adobe, conversely, has moved to a subscription model wherein you pay every month for access to the software. So the "upgrade" path is built into the model.
(2) According to that ReUp article, Apple hasn't updated FCPX in over a year!
According to Apple, there have been no major FCPX feature updates for a year. It looks like they've been saving the new features for 10.1.
Likely, as the article notes, because they want to say some snappy features that will entice users to upgrade both the software as well as the hardware (i.e. new Mac Pro). Avid does this as well. Instead of rolling out new features ASAP they hold them back until the next large upgrade offering so that users will jump to the next version. Adobe was on this same cycle not more than a year ago. One of the strongest benefits of the Creative Cloud approach is that Adobe doesn't have to entice users to upgrade anymore. If you're paid up, you can download the latest version whenever you want. So Adobe doesn't have to prioritize bug fixes vs. feature updates anymore. It can do both at the same time.
Is one model better than the other? No. They're just different. It remains questionable if the subscription model Adobe holds to currently will pan out over time. However, it does offer some staggering differences between Apple/Avid and Adobe.