In any particular situation there's an interplay between the environment and your mind. What can be done (i.e. next actions) at any moment is determined by both of these.
For me, contexts clearly fall in the environment realm. They simply define the environment that you're in.
Sometimes, like you, I am in an environment where a lot of things can be done. When I'm at home I select: @Home, @Calls, @MacBook Air, @MacBook Air Wifi, @iPhone, @iPhone 4G, @iPhone Wifi, @iPad, @iPad Wifi, and @Pencil & Paper. Obviously, I have a ton of next actions under these. And that's exactly how it's supposed to be because that is the reality of the environment that I'm in. That's what Contexts are supposed to do. Contexts don't pick something for me to do, they only define the negative, they define what I can't do.
So where do "I" come in? What's the other side of this equation? Where's the "yang" to the "yin"? Where does the mind come in? It's not next actions, it's projects.
Project categorizations are mostly "mind" related. They're what things mean to me. They're things I want to achieve. They're the "wildly successful outcomes" we've already envisioned. It's very important to have a way to simply see all your projects (maybe just by area of focus) but uncluttered with all the actions associated with them. By browsing all your projects you can pretty quickly use your intuition to decide what to work on. Opening a program takes no effort for me if it's done AFTER I've scanned my projects and decided on what's most appropriate to do at that time.
So I think the problem is not we have a lot of things to do in our contexts, the problem is that we can't decide what do to by looking at next actions. We decide where we want to go by looking at outcomes, by looking at projects. Next actions are simply the dumb next physical action to do to reach that goal. No thinking done there, that should have already been done when we created the next action.