Nagol said:
What are the characters attempting to accomplish? <-- this is typically defined in systems I've seen
What are the characters risking? <-- this is typically undefined, nothing, or the risk is the encounter devolves into a combat in systems I've seen
How difficult is the opposition? <-- this is typically handwaved or set to "appropriate for the party level" in systems I've seen
I think you're right, here. There's a real need to define these things. If we look at exploration in general:
The players are trying to accomplish getting from Point A to Point B. They don't necessarily know where Point B is (ie: it could be a MacGuffin or a hidden lair or whatnot), but they know they gotta get there.
The players are risking...ultimately, I think, they're risking their lives. In early editions, the random encounter was potentially deadly. So were some of 3e's weather hazards. Starvation and thirst can be deadly, and you could catch diseases, or break something and be forced to ground. This has been largely de-fanged and handwaved because it's been complicated to actually account for in the systems we have, but I think this is an area where we can have a lot of improvement. It should be
scary to go on a three day's journey into the wilderness, not just "time passes, and you arrive at the next combat encounter." Traps fall into the same camp -- falling into a pit should be possibly deadly, not just "lost some HP!" and a continuing on.
That's, I think, why "time" becomes an issue. Time itself isn't a problem, but if you spend more time in a hazardous environment, that's just more "actions" the environment gets against you. The more encounters you face, the more your supplies dwindle, the more you hit potentially deadly hazards.
The opposition is mostly environmental, but it can range in difficulty. Walking a well-worn path shouldn't be very risky (maybe some bandits or something), but walking into trackless wilderness should be potentially deadly for low-level characters, and things like blizzards and tornadoes should still be potentially deadly even for high-level characters. At the highest levels, they can maybe deal with supernatural weather -- acid snow or blood rains or whatever.
I think a big thing is working on that deadliness of the opposition. Random encounters haven't been scary for a while now...maybe it's time to bring back the idea of
potentially dying when you go into an unexplored section of the map, not from monsters, but simply from a hostile environment.