I always thought the standard in these situations was to take a product off the store but to leave it on download lists/histories so previous purchasers could still access it. If that's not happening in these cases you're right to kick up a stink about it. It's fine to restrict access going forward, but not retroactively for purchasers, and certainly not without good compensation in very pressing circumstances (e.g. if the company had been legally obliged to take it off for everyone).
Persona conjecture but based on experience I have a suspicion it's more true than not - Companies have, so far, coasted on the DD "rights" issue because it's all new, and nothing truly major has come up. It's not unlike the epic PSN outage was really kinda new thing and unexplored territory. In that case, Sony ALSO didn't really respond all that well to an unexpected development. (Slow to inform users, anemic apology and "compensation", lack of transparency on when PSN might return.)
With DD purchases, it's relatively simple even in a logistical sense to keep the files for past purchases on servers so that people can redownload, in the even that something comes up and prevents further sales of the product. But that's a passive solution to potential bumps down the road. It doesn't require planning for investments of time, money, or personnel to deal with more serious issues.
For example, one problem with software is that much, or even most, of the time, the original development team isn't available a short while after the software is released, to perform further modifications to the software. In many cases the source code and assets for compiling a new version, especially with games, may be difficult or expensive to access.
When something happens like a DD game actually causing problems for the platform (such as security breaches), there's even odds that it won't be trivial to "fix the game" and re-upload the file. Way too many inconveniences could prevent a cheap and quick solution. In that case, the most expedient thing for the platform holder to do... is nuke the game from orbit, and remove the possibility of anyone from either getting access to the file ever again.
From the corporate perspective, it's simple, fast, a sure fix, and most of all... cheap.
Problem is it violates the end user and customer.
In the case of these particular PSP games in the current situation, I wouldn't doubt that it's probably not possible to simply "fix" the exploits in either game and re-upload a fresh version because development assets and resources have long since vanished and moved on. It might cost Sony a noticeable fee, either in money, or time, or both, to actually create new versions of these old games.
Perhaps its possible to rule out the exploits with a Vita firmware update. But if it's not, then the games simply must go and will never return.
Which means its a rather serious problem that the platform holder never allowed for in their planning - how to secure the purchases of a customer if more serious issues than "we lost the license to sell new copies" crops up down the road. Because from what I can see, that is just about the ONLY potential future problem than any of the major platform holders for DD have accounted for. Everything else... is murky. And companies tend to do things for their own benefit and convenience rather than good relations with the public.
So, I think how Sony plays this hand in the near future will be very interesting to see. FYI, while one of the folks involved has indeed gotten some form of communication back, don't forget what happened with the online pass debacle on the Vita a few weeks go... some call / email reps were telling people strange and worrying things that ended up being overruled by higher ups once a real solution was found.
Come on, everytime pretty much EVER something like this has happened people have gotten refunds and something small to compensate.
While this is basically true, I think the bigger concern over the future of DD is what has a lot of people taken aback. It's not just about the refunds (though that's important). It's more disturbing that one of the points of DD is being undercut so readily. Bad precedent for the future.