That is a play style that has nothing to do with the edition. It's called sandbox. You can do it with any RPG or any D&D edition. I was there in the early 80s and we played different types of campaigns. Some were sandbox, others were arc story style, some pure dungeon crawl hack & slash.
Also, "Run Away!" is always an option regardless of the edition. If players, in my campaigns, misjudge the challenge in front of of them, their PCs will die!
This is nothing to do with being a sandbox. My description here applies equally to a small dungeon, mega dungeon, wilderness trek or sandbox approach.
Run away is an option in any edition, but one rarely taken these days because of the change in philosophy. This philosophy shift is shown by:
encounter budgets - creating an expectation for the GM that there will be a certain amount of “appropriate“ encounters in an adventure. Which has also created a certain cultural shift in player mind set that nothing set in front of them will be impossible (as it should be appropriate to our level) so let’s try and take it. You did have some level of balance in terms of monster level generally equal to dungeon level but it wasn’t necessarily on an encounter by encounter basis.
shifting experience points emphasis. Gold no longer has xp value and monsters have more xp attached to them. They were worth naff all in earlier editions, the bigger emphasis was on the treasure, so why waste time in combat?
The more detailed combat rules have slowed combat down, making it more of an event. Which has deprecated wandering monsters in dungeons (as it would take up too much of a session play time) which were supposed to be a penalty for taking too long in a dungeon and a resource hit, again, worth little xp.
I’m not saying one play style is inherently better than the other. do what’s fun at your table. You can certainly try and play older editions in A “newer edition style” and vice versa (see Dragonlance), but understand that you are fighting against assumptions that are written in the rules. And I’m sure many did (Take what you want from a rule set and play with what works for your table, but I’m talking about the RAW) . it is to do with edition, it is there in the rule books. Od&d, b/x, AD&D. You can start to see the shift a little in 2nd edition with a deprecation of these rules and a shift in the published adventures. By 3.5 this transition was complete.
