If anything, they are more useful and cool now than every before. That is because each core game has 3 methods to play, one of which happens to be NARRATIVE. There is nothing more narrative than a well organized campaign, and a map based one at that. I really wish I could play in one. Add to that the Crusade system in 40k AND you are just begging for a reason to do campaigns.
And then there are specialist games too. Adeptus Titanicus and Aeronautica Imperialis both lend them selves well to a map based campaign system, Titanicus in particular. And then the big daddy of Horus Heresy itself. All of these games expansions ARE campaign books.
Heck, with some ingeniuty and clever hobbying, you could even make a great underhive map for Necromunda, allowing you to track gang territory and add some depth and realism to raids and the game as a whole.
The potential to work these into supplements, like they used to with WHFB with things like Blood in the Badlands, is incredibly high.
They would also make the perfect feature for a set of articles over the course of several issues of White Dwarf, and could cover multiple aspects of the hobby, from modeling your map to playing the campaign. And then these would be the perfect tool to utilize to introduce fun new narrative based rules, stratagems and mini campaign in both White Dward and Chapter Approved or the General's Handbook. Environmental and Warzone type rules are the most obvious, giving in game effects for fighting in a jungle or a rad desert, ice wastes or an urban sprawl.
It would be even cooler if then there were faction specific or bonus tiles sold in specific kits. Special tile in a White Dwarf. Faction tile in a start collecting box. Manufactorum tiles in the 40k terrain kit. Civitas tile in Titanicus Terrain. Etc. Etc. You get the picture. Give people a reason and desire to get a full set of tiles in their Planetary/Mighty Empires expansion, and then reward people with those expansions for continuing to purchase GW kits and armies.
There is just a ton of reasons why this should happen and none why it shouldn't.
Now I understand there are plenty of 3d printing options out there for these, and that really is a great solution if you want a table. But in terms of full support it is lacking. I really believe the modern GW could really maximize their supplements with a tool like this, just flushing out campaign rules and providing even greater reasons to use things like the Crusade System.
And there is a PERFECT opportunity coming up for GW to bring this system back, as there is game coming with a locked map, with factions tied to specific regions, and the greatest potential for meaningful, impactful campaign play. I am of course talking about
Imagine setting up your Empire Map and fighting off the forces of Archaon coming from the North, or challenging other players for control of the Border Princes. Think of purging woodlands of Chaos Beastman or marching out to besiege a Dwarven hold.
C'mon GW. This is basically a money printer for you guys. Easy to produce cheaply, yet highly desirable and useable by many many hobbyists. The fact there are so many 3d printing options out there for it only reinforces that it is a desirable commodity. So what are you waiting for?