Electric assist bikes -- "Foolish or awesome?": Absolutely freakin' awesome.
I've modified several bikes for electric assist and absolutely love it. I've been commuting every day about 18 km round-trip to work, and just last night fired up my ample lights and rode in the dark to my friends 3 km away, rather than drive the car there. The electric makes it so easy that the excuses are much diminished.
I have to believe the comments about heaviness are based on old technology. With moderate sized lithium batteries and an "assist"-level motor (I recommend 350 W geared) it does not add a lot. My complete bike is 35 pounds total. Maybe that sounds like a lot if you are used to feather-weight $2000 bikes, but believe me, with an extra 500 W surge (which a nominal 350 W motor can do) compared to your legs 100-150 W or so, the bike feels light enough.
I recommend converting a bike to electric rather than buying, if you can manage some basic wiring and connections. Such bikes tend to look more normal and can be built for quite a bit less. Plus in true mustachian style, you will have grown your skills and know how to fix it yourself when the time comes. If you are clever, they can be made very "stealth" -- i.e. no one needs to know it is electric. I've had people standing beside my bike and I tell them it is electric and they stare in at it trying to figure out where the battery and the motor is.
One important point is to distribute the weight well. Mine is a front geared motor, with the batteries inside the triangle, and the controller at the back. Batteries low and inside like that make the feel of the bike more normal.
Another advantage of electric bikes is that they are a hybrid human-electric combination -- in my case me driving the back wheels, the motor driving the front (by the way, the all-wheel drive is helpful in winter riding). I can choose to use more or less electric depending on my mood or energy level. It extends the range you will consider going. It also ups your average speed so commuting time is cut down.
Anyone interested in electric bicycles should go over to
http://endless-sphere.com/forums. Read my post there in the technical reference area for some basic background (
http://endless-sphere.com/forums/viewtopic.php?f=16&t=26619). Poke around or ask questions for the latest recommendations on good values kits.