PS+ is worth it for games alone. I'd be annoyed if cross saves/online multi were the only things behind paywall, but as a service I have no problems paying for it.
It'd be nice if the features I want were tiered out to where I could pay only for online and cloud saving if I got a PS4, and get none of the free games.
I had PS+ for a year, and never really played the free games I got, and when I ended up with only a Vita the title output eventually slowed to where I knew I couldn't easily recoup my cost for the subscription in PS+ discounts of 10-30% unless I bought things only because they were on sale and only when they were on sale. I don't want to be in that "should I buy it or wait" dance. I always buy physical if it's available and almost always on day 1 if I want something. It's only in the last year or so that day 1 discounts have become a regular thing, and it's still chance to whether a title I'm interested in will have one. I don't want anything in my library, even if it's digital-only, to become inactive when I inevitably let my subscription lapse. Say I got something free on PS+ and the publisher lets the license expire or removes it from the store - in that case, even if I wanted to buy the game outright after my subscription finally lapses, I probably wouldn't be able to. I also don't like when I can't capitalize on a dirt cheap sale on something that's been free on PS+ and is still "owned" in my DL history.
I know I've read about people who've had the online pass for Soul Sacrifice recategorized as a PS+ item by downloading the digital copy when it was free, even though they own the physical copy. The way PS+ freebies has effected Retro City Rampage DX, which is a free upgrade on every other non-Sony platform, really annoys me too.
I know why people like it and I can explain why it's a great deal for 99% of people, but it's not for me. I never am in a position to buy PS+ super cheap on black friday/cyber monday either. I won't get it again until I have to on PS4, so I can go play LBP3 online.
Personally, I would rather pay for a service that works universally and that I have full control over and understand as opposed to have a service for free that is random and wonky.
That's how I feel about pretty much everything I just detailed. No control, random, wonky. The option to get automatic cloud saving with a few hitches, as you said, would still be a nice option to have... and if people want full control they could still pay for that.
Even if you pay for PS+ and use cloud saving... you still need to back up your Vita games if you have any extensive DLC and patches for it, unless you want to redownload those in order to make your imported save compatible. I'd dread having to redownload all my LittleBigPlanet DLC one by one for literally hours again (select, wait, confirm, wait, install, repeat), for example. If legacy PSN, Vita saves and data were handled differently, that would definitely be cloud data management I'd consider worth paying for on it's own.