The fundamental problem with "taking it into your own hands" is that some of the apps being proposed here (Google+, HBO Go, etc) require the use of private interfaces to make them anything but shadows of the real thing. And those APIs aren't made available (sometimes even the basic ones) for a reason. HBO Go wouldn't even let you touch their infrastructure, much less expose an API to reverse engineer in the first place given the sensitive user information that ties into cable service user databases. You'd get sued out of existence in the HBO Go case, and a really feature-light app with Google+ not worth using since the public API is seriously crap and lacking almost everything that would make it compelling.
Look at the WhatsApp situation for another great reason why "taking it into your own hands" piggybacking on popular companies that produce their own first-party applications is usually a bad thing. Even for those which a reverse engineered API exists, your app (and the user experience, as a result) are at the whim of any changes they make. In the WhatsApp case, a single API change to authentication has essentially crippled the app into uselessness for a while now--with no ETA.
Now imagine how its users must feel getting jerked around, having made the choice to use the app not realizing how unstable it would be. If you're a user of webOS excited to finally have WhatsApp, this situation exposes webOS' weaknesses with a neon red light and makes other platforms with a legitimate client look a hell of a lot better in comparison. There's no better advertisement for your competition than your own failure.
And Apollo? That's living on borrowed time, as it, too, uses reverse-engineered APIs that could go dark at any time with a chance of being irrecoverable. And it's piggybacking on a publicly-traded company (Pandora) with plenty of legal representation behind it. I commend the developers for having the balls to disregard that fact at their own peril.
Or, to take it from another angle, look at Twitter's active hostility against third-party app developers in order to drive them away in favor of their own apps, making them follow extremely oppressive guidelines meant to limit their usefulness and user reach. Tweetbot for the Mac (among other top-tier clients) are facing seriously negative future outlooks because of it--so much so that the makers of Tweetbot instead decided to support App.net going forward since Twitter restricts the number of user tokens...and thus their ability to sell copies of the app after a certain time. The only reason webOS Twitter clients haven't had to worry is because the remaining userbase is only a fraction of a fraction of the limit larger clients on other platforms are facing.
So, my point here is to be very careful which app ideas you move forward with, especially where it concerns piggybacking on another company's services. ****ing off remaining webOS users and making webOS devs look like a band of amateurs (that didn't think things through) to companies that may be interested in releasing hardware for it isn't a good idea. In fact, it's a really, really bad one. Each and every visible failure drives people--and potential support from elsewhere--away from the platform out of frustration and/or the perception of those supporting the platform not having their **** together.
Do serious and rigorous research ahead of time to evaluate which app ideas are actually doable to a 100% legal, professional, and polished degree and run with those. Study the APIs, the terms of service, legal and brand standards requirements, estimate the development complexity involved, and make sure the person doing it is a developer that can properly evaluate all of those things. Make sure each and every one of those apps is a beacon to anyone seeing or using it rather than a rushed, ugly piece of code of dubious legality.
But, stepping back a bit, this seems like yet another one of those threads around here where someone gets big ideas to resurrect webOS's chances with users or potential OEMs. Everyone talks about what should be done in exhaustive detail and pumps the crowd up, but without fail not much ever gets done to actually make it happen and it just ends up driving even more users of the platform away. And worse, the ideas are presented as realistic when they actually require a legion of developers that simply no longer exist in the webOS community, with no replacements in sight. Those developers aren't coming back, either; they've moved on.
As a quick sidebar, this is just a recent, representative sample of the things I've seen from ex-webOS devs:
So, these ideas are nice to think about, but have no basis at all in the reality of the situation, especially where it involves level of effort (LoE) required, much less the number of qualified webOS developers remaining to make it happen. If somehow you guys did manage to find the time and the people to code the 30-40 seriously professional and polished top-tier apps it'll take to get the attention of anyone--some in that list taking entire teams months to develop, usually--then godspeed. Anything's possible. Just be smart about it and don't screw your users around by half-assing it just to say you got the app out there--or open yourself up to legal liability in the process.
Lest you think I'm being harsh, considering some of the ideas in this thread being thrown around with no concern being expressed about actual feasibility, I'm actually being pretty damned nice.