Gall says nothing about the simplest thing, only that complex systems grow out of simple small ones.
My point is just that the way Gall's Law maps to something like Extreme Programming is through, "the simplest thing that could possibly work." When one is starting out a new project, that is precisely how one applies Gall's Law.
"the simplest thing that could possibly work" might not actually (or always) be something that a complex later system can evolve out of.
Software shouldn't be that limited. In particular, of you are using principles/tactics like DRY and Law of Demeter, you should be able to grow your project into a more complex one. (Or, in preparation for growth, apply those and then refactor.)
I'm reminded of a comment by Alan Kay about how you don't want the lowest stratum of a system to be too simple.
This is probably because the lowest stratum can be the hardest to change. In software, it's even possible to take away the foundations and exchange them! I've worked with people who have done it. (Migrate an app from an Object Database to a relational one, for example.)
My point is just that the way Gall's Law maps to something like Extreme Programming is through, "the simplest thing that could possibly work." When one is starting out a new project, that is precisely how one applies Gall's Law.
"the simplest thing that could possibly work" might not actually (or always) be something that a complex later system can evolve out of.
Software shouldn't be that limited. In particular, of you are using principles/tactics like DRY and Law of Demeter, you should be able to grow your project into a more complex one. (Or, in preparation for growth, apply those and then refactor.)
I'm reminded of a comment by Alan Kay about how you don't want the lowest stratum of a system to be too simple.
This is probably because the lowest stratum can be the hardest to change. In software, it's even possible to take away the foundations and exchange them! I've worked with people who have done it. (Migrate an app from an Object Database to a relational one, for example.)