While I'm playing and use the tactical view I can't help to think that seeing icons for the installed major modules would be very useful, it also would fill the view a little more, since it's rather empty. So here is this simple suggestion, add icons for the installed major modules (and if it's being operated) and make them visible on the tactical view, this would help as a simple cue for checking how many of every major modules are in play, while also adding a little extra to the overall experience.

Sometimes I feel that during the game I spend more time observing tactical view than the dungeon itself. It's very easy to spot powered/unpowered rooms, monster spawn points and heroes position with it. I think that if developers would place all the information on the tactical view (including modules) then players would just stick to this view and zoom in hardly ever. IMO incomplete information on the tactical view adds more challenge.

I'm not talking about all the information and I hardly believe players would miss the beautiful pixel-art of Dungeon of the Endless for an idea of tactical advantage. I mostly zoom-out to send heroes to rooms that would require to move the normal view or to quickly move the normal, apart from powering and unpowering rooms. Knowing which powered rooms are being exploited (have a major module placed) and which resource it is would save the players from having to calculate from the resource income or spanning across the entire dungeon. Since we are talking about the build phase and not door opening phase, I believe there's no change on the difficulty of the game, the challenge comes when you open a door, knowing this information doesn't change a thing on that beautiful moment.