Generally we always consider carefully what data to return in each API call. Performance dictates less data should be returned while easy-of-use and reduction of API calls dictates the opposite.
I can't change this right now, but I can tell you that we have started work on making it possible to specify exactly what data to return in each API call. This work has however just started and there is still a lot to do before we can make it available. Until then I am afraid you will have to make multiple calls.
That said we generally recommend that integrations through the API focus on apps, as they are generally much more flexible than tasks and lend themselves better to modeling of work flows.