I'm pretty sure that if I could afford the flying car, I could afford an estate large enough to have ... and money enough to construct ... a runway - - plus whatever pesky license fee I need to run a private airport. Pfft, dollars? Who cares?

Screw that - I want a Light Cycle!

Wow, a flying car... and only 10 years behind schedule!

I'm sure they could make it a flying boat car by adding those float things like "de plane" on Fantasy Island, and putting the wheels there. If you're going to plunk down $200K for a flying car, why not an extra $50K for a flying boat car?

Part of the deal with the flying car is that it actually functions as a car, shrinking down to car size, so you can drive to and from airports. I think boat floats would negate that.

Nonsense. If wings can be tucked up or out of the way somehow so you can drive, so can boat floats.

But they'd add weight

The wings fold upward. If the floats are attached to the bottom of the wings I don't see how that would work.

I know a car that can do all three.

am I seriously joining a discussion of the real-world-logistics of creating a boatplanecar?

One would presume that if the goal were to design a boatplanecar, the designers would not be limited in their design options to "okay, attach floats to this existing planecar". Just because there's no way to attach floats to the wings-as-designed doesn't mean it's inconceivable that floats can be attached and fold away with some alternate design. By your argument, they should have given up on designing the Transition. I mean, if you attach folding wings to a car, they'll block the doors, there's no way that could work.