The intention is probably to get to a more sandbox style of role-playing. However I find that this causes a problem for preparation: I find that D&D sessions where the DM is well prepared run a lot smoother. If the sandbox style is too open and the DM *can’t* prepare and has to improvise everything, the game session becomes a lot more laborious. That is especially true if the DM uses visual aids, like I do: Battle maps, 3D printed miniatures, handouts, etc. all require preparation.
The advantages of full sandbox mode of infinite freedom are also somewhat illusionary. Most of the time players act on little or limited information. The freedom to go north or south isn’t worth much if the decision isn’t meaningful because you have no idea what happens if you go north or if you go south. But of course full sandbox or strictly linear gameplay aren’t the only two options, there are compromises in between the two. And that is what I will be going for in my campaigns in 2018. Basically I will present the players options, but with sufficient information to make each option meaningful. Instead of telling them that they can go in any compass direction they want (which isn’t how humans tend to travel anyway), I present them with a fork in the road with road signs to two different places, and some knowledge (e.g. with history checks or from passing travelers) what is going on in those two places. A meaningful choice between 2 locations is better than full freedom to go anywhere, just to face the same random encounter tables because otherwise there isn’t anything there.
For my Princes of the Apocalypse campaign this is already working well enough. I gave the players some information about the evil elemental cults, including an idea of relative strength. They usually know about at least 2 different locations where they could go next, and what cult is likely to be there. Which means I can prepare both places and be prepared for either choice. But I did use magical portals to block off the deeper dungeons, which not only I would be not prepared for, but which would also be not much fun, being much higher in level than the players.
Next year I’ll try to start a new campaign with new players at my local role-playing club, using the Out of the Abyss campaign setting. So over the holidays I have time to read the book front to cover, and fill out the blanks with the missing story line and alternative options. As I recently wrote, I learned from a good DM / group on YouTube that I shouldn’t worry too much about the story line, but rather make sure that there is enough opportunity for players to contribute to the story with their own ideas. Which means presenting situations in a way that make it clear that players can do other things than just roll initiative and attack. I still believe good tactical combat encounters are important and they are usually fun to play for the players, but they aren’t all there is to Dungeons & Dragons.