Systems being open have a trickle down effect of enabling many creators - that means if your kids dont like the mainstream toys they can very likely find some toys created by some small creator. Innovation is correlated to systems being open. Without open and free operating systems / compilers / debuggers we would not be seeing the proliferation of technology that we see today. Advocating for openness does not imply the expectation that every single user will use the schematics and source code to build things from scratch, it just implies that the subset of users who are unhappy with the status quo have some means of changing it.