Instill like the idea of contexts and have gotten a lot of mileage out of a fairly vanilla GTD-canonical list of them over the years, but I can definitely see your point. Between having a smartphone that has ubiquitous Internet and Office capabilities and the fact that I've been working from home this year, I feel contexts are starting to lose their punch.
I do still think a few kinds of context lists still hold all of their power: Errands (which you mention), Agendas, and travel-specific (when-in-city-x or at-conference-y) lists are still gold to me. I've also started trying to sort Next Actions by type of task--@Email or @Coding or @Drafts, not @Computer--to keep the main list shorter and group like items for batch processing.
But I feel a GTD reboot coming on, and I may try a more classic list again. We'll see...