I notice, that the circuit shown in post #1 corresponds to the classical 7474, if you omit the asynchronous control signals. In so far it's a good representative, although not exactly functionally equivalent to the TG design. And I was apparently wrong by claiming it's not edge triggered. It actually is, although the structure is less clear than the TG design.
I think, the answer is a pure technology matter. All bipolar FFs are using the gate structure, all CMOS FFs the lower transistor count TG design.