While the layout editor does just about everything, some of use are use to tile editors and like to create tilesets for our games. If anything, just allow us to snap to a grid or something for tile based mapping.
In a lot of games there are message boxes, very common amongst RPGs. Some have portraits, some have face icons. And each message box generally works the same. You have letter by letter dialog, and if somethings important you would color that word or phrase.
Have no idea if the newest version of python will work with Construct, but it'd be a great feature to update.
While anything RPG Related can be done in Construct, built in events will help as well. Such as weather effects, day/night effects, wind effects(also should have a strong setting so the player walks slower if the wind is at a strong setting). Emotion icons, these are basically just your love, "!", kind of icons. Basically just expression icons that pop up over the player during or after a message sequence.
While this really should be left to phython or constructs human events system, a menu editor should be added as it can save a ton of time between play testing over and over. Also, it'll create a python file in the games folder(wherever python files are saved) with the menus code.
This really explains itself, basically a hud editor where you can design the hud for your game right in front of you. This also can be done within python very easily but some things are better off with an editor.
This belongs with the menu editor idea, where you can design your save/load menus and make them so they're not so..ameturish..
But minus these, construct is a very all around awesome 2D game Engine that can really do just about everything. This is 1 engine where you can believe what the developers tell you.