The biggest problem with something like Adobe' Creative Cloud and Office 365 is that you must have access to the software to be able to make use of your data created within it. If you rent the software, you "rent" your data created with it. For example, if you're a struggling art student building a portfolio with Illustrator and Photoshop and assembling it in InDesign, and you find yourself in a tough but temporary financial spot (near end of term with the next loan/grant/Daddy's stipend payout a month out, for example), and you decide to drop your $50 CC subscription for a month so you can lighten the load, well guess what? Now you not only lose the ability to work on your portfolio, but unless you had the forethought to export to other formats, you lose access to all of your work when you lose access to the software. Even paying customers have subscription "hiccups" that screw them over, with the infamous surprise Office deactivation while on an airplane or otherwise unable to service the activation system having become fodder for many an angry article.

Rental software/SaaS and software activation generally are, in my opinion, very unethical practices that should be smacked down at every opportunity. I don't like to use legislation to fix problems but I think that software activation cracking should be made 100% clear-cut legal instead of being the grey area it is today. If you buy software but it has mandatory vendor activation, you don't actually own it after all. I do understand that SaaS serves a market and I don't have as much of a problem with it when it's something where the data is easily exported to a usable format even if your license expires (such as a customer database being dumped to a pile of CSVs that can be migrated into something else), but even in such cases, the data is unusable without the software until you come up with a way (or pay someone) to migrate it to another system where it can be used, so I still have a problem with it.