You will always find some (edge) case who can profit from these kind of schemes - an amateur photographer for example with Adobe CC or somebody who uses all the jetbrain tools - but there are a lot of cases that are a different and really don't have any benefits of using SAAS.
In Flanders we have a saying that goes a bit like this: "all small things makes on big thing". The personal problem that I have is that if I would add all those "inexpensive" subscriptions of services it will add up very fast to a point that it is becoming really expensive. I don't buy all software in a single month or can even wait for upgrading if an older version is good enough for me, with SAASS that is not the case.
But I have the same opinion that this race to convert all commercial software to SAAS will be beneficial for OSS alternatives. Personally I would even go as far as donating (or crowdfund) (for the same amount that I would give to jetbrains) to an OSS project, if that means that I would get an alternative that I don't need to "rent".
PS Alternatives: Acorn ($25), Pixelmator ($30), Affinity Photo ($50)
Illustrator alternatives: Sketch ($99), Affinity Designer ($50), iDraw ($25), Canvas Draw ($99)
And you know what? All of these options are far lighter than the Adobe behemoths while providing all the most relevant functionality and looking and feeling like real Mac apps instead of half-assed ports, all while taking advantage of the best part of the OS. Here in SV people I know in design are switching away from Adobe in spades.
If companies like Adobe can’t exist without subscriptions, maybe it means that large software companies that produce gargantuan beasts of applications are going out of style. Small indie teams producing lean, maintainable, focused apps are the way forward.