I agree the battery packs are and will be installed in different locations in different cars. The pack changing station does get more complex when changing multiple smaller batteries, rather than just one big one in a standardized location. There has been enough stories on industrial robots on slashdot to make me consider this is a fairly trivial problem to solve compared to lots of other stuff we are capable of.
Even so I don't think the cost for the swapping station really comes in to play. You personally don't need to own one and businesses will recover the capital over time. The up front cost is going to be greater, but when done properly, you can service many different types of EVs with a single station and enable a far greater freedoms in car design and weight distribution, just the thing you're talking about. With swappable batteries you need to be able to access them from the outside of the vehicle, but that's about it.
If Better Place is able to achieve reliable coupling with their scheme, I wouldn't think say 5 smaller couplings would be unworkable. When you increase the number of couplings, you decrease the amount of current each has to carry, making each one cheaper. This does not just simply add up to 5 times the connection problem compared to having just one.
For the packaging, I don't think that in any one of the cars you listed the battery pack is a single cell. Some more packaging is probably required, but given a reasonable size for a exchangeable unit, I don't see the difference being that great. Also for the cost of the pack, you would be leasing them anyway.
You listed a few profiles for batteries; two in fact. High power and low power. The amount of energy is just the number of the packs in the EV. The lease on a high power battery is likely to cost more. Not unlike premium fuel that costs more over the regular stuff. Also when battery tech improves, the capacity and the power output increase, but this can be negotiated between the EV and the battery.
Quick charging is, while also solvable, a completely different beast. With the swapping stations you can charge the batteries a bit slower anticipating demand, with less need for expensive high-voltage high-amperage infrastructure all over the place when compared to ubiquitous quick charging.
I think the swapping stations and standardization are a good idea, at least for the time being. My musings just give the idea some more versatility compared to the single-big-pack model. Maybe when battery tech improves further and we come up with economical superconductors the picture would be very much in favor of dumping the swapping stations.