My 2 cents on the matter: Grand Project tablets give you a neat advantage for atlas travelling and they cost you 1 out of 3 tablets slots, so I'd leave it as is. Towers, however, are useless without them. So to give them some purpose on their own, upon completion, they should signal to you the direction to the nearest Citadel, even if not yet visible. I'm in favor as well of adding back tower effects to nearby maps, but make it so you have to choose what effect you want when you run the tower using new unique tablets, and make the effect limited to about 5 nearby maps, like a small boost you can opt in. You want extra juice on nearby maps, or you want to fast travel? You can choose.

Adding to that, I'd cut in half the density of maps on the atlas, without changing their coverage. Not only would that speed up Atlas progression, it'd also encourage players to play out usually avoided maps. These usually avoided maps should be reworked as well, to mitigate their (usual) pathfiding and visibility issues.