The Mappack has been out for -years- and the developers never said anything about it, nor did they do anything to attempt to hinder its use.If the designers and developers intended for map pack to be used, they would have included it with the UI.
The Mappack takes time to update and develop; they already have a full plate as it is. Maybe, just maybe, the Developers not only don't mind its use, but I'd be willing to bet at least one developer even uses it themselves!
And there really is very little difference between using a Mappack and going to that website that has a google maps version of Istaria with the very same markers all put out, except that it is not accessible in-game like the Mappack is.
The Developers know that not everyone can alt-tab out of Istaria; I for one, cannot. I tried it on five different machines and it crashes every stinking time on all five machines I've ever played Istaria on.
Face it: If the developers had anything against us using Mappack, they would have either banned its use, or changed the Map UI to "break" Mappack, or issued a Cease-and-Desist letter to Mappack's creator(s)/author(s)/maintainer(s).