Would it be more cost and weight effective to do a direct drive then? And what would that entail?
That depends what you mean by "direct drive", but anything replacing the car's original multi-speed transmission with fixed-ratio reduction gear set would be lighter, simpler, and more compact.
Literally, it means that something drives something else, directly, with no intervening mechanism. In practice in an EV that could mean a motor driving a wheel without any gearing between them - that's only done with in-wheel motors, and no one is suggesting that (yet), because it's not likely to be a good idea.
Usually in this context, it means a motor driving the input of a final drive unit (diff) or axle without any reduction gearing between them. That can mean via a shaft (such as from a motor mounted where the transmission was) to the original final drive (perhaps with a different ring-and-pinion gear set in the final drive for an "axle ratio" with more reduction). It can also mean the motor mounted right onto the front of the final drive, if there is room there (and there usually isn't, but it has been done). Regardless of location, this can work well if the motor can produce enough torque for the result (after final drive multiplication) to be adequate at low speed, and if the motor speed corresponding to driving speeds allows the motor to produce enough power for those speeds. That's a really low-speed motor compared to what is normally used in modern EVs. You have only a single stage of reduction gearing (the BMW ring and pinion gears) with a ratio in the range of 3:1 to 5:1, instead of the two stages of reduction gearing in a typical EV transaxle with an overall ratio in the range of 7:1 to 10:1.
Im a little biased, But I say make it direct drive, Ideally a telsa motor, but with lots of modding skills you could use a leaf motor and transaxle too.
Using a complete drive unit (motor and transaxle) from a production EV makes a lot of sense. It's not "direct drive" in any sense, but it's still a good solution.
The Tesla "motor" would be a complete drive unit with transaxle, just like the Leaf unit.