A test in noPassthrough provides very limited test coverage, whereas tests in jstests/core are run with all the configurations / fault tolerance modes available in our passthroughs. They will also be picked up by any new suite that is added in the future, so in that way they help with future coverage as well.

If this is too much work for QE alone, and some of this work is outside QE's scope but still covers query stuff / aggregation, consider filing a ticket for the other teams within the Query org