Firstly, I thought the fact that DFHack is built on DF as a community project out to mean that anything in there would be not only permitted to be included into DF itself, but rather encouraged. In my view, there's no higher praise than to get your ideas incorporated into the project itself.
When it comes to the Embark Assistant, its design is based on DF's find function that's then expanded upon based on what various people may want to search for. The ideal state of affairs would be that it was made redundant as DF provided all the functionality in its finder. Thus, I'd be delighted to see all or some of the functionality incorporated in the game.
When on the train of trying to push utilities into the game, tweak_map.lua is a script that acts as an alternative to the built in (and hopelessly useless mouse only driven) World Painter. The key difference is that apart from allowing the user to set PSV values, it also allows the player to specify the biome, at which point it adjusts the affected PSV values to about the middle of the range. In addition to allowing players to select biomes (among the legal ones for the latitude), it also displays the current biome (using letter coding, but tiles would allow that to be done using biome tiles). If there's any logic in the script or ideas in it that would be useful in a brand new World Painter, feel free to use it. Scrapping a utility because it's no longer needed is good indeed.