I strongly agree with @pix3l and @callum-gander not only it might be kinda anoying to always explicitely specify all the fields to return, but also, and this is why I searched for this topic - as I’m used to take advantage of Open API schema to get types from, in combination with documentation plugin, all the fields are optional, which would in my case lead to having code full of ?.?.? and I will probably choose GraphQl after all, because in it’s case such field selection is by its design and one of the biggest advantages without any doubt…
On the other hand I realize that by strapi’s nature of creating the api’s dynamically this is probably the only way how to give the client the option of selecting what to fetch - model situation I wanna get only few fields for the list of articles, but all of it’s contents on it’s detail page. In case of relations, I would much rather see a cleaner REST pattern and having to call mutiple endpoints, or a combination of having the loaded to some level automatically, dunno 
I realize I’m just complaining without offering any ideas how to deal with this but I wanted to share my thoughts anyway… Perhaps implementing a way of providing some sort of views/dto/endpoint definitions in form of another json schemes? Just a quick thought…
Anyway, I love strapi so far and it’s very positive to see how live the community seems to be 
EDIT: For the type generation purposes, it just occured to me, that maybe it might be up for developing more soffisticated generic interfaces that take the populate fileds into consideration