Speaking of substitutions, I don't believe there is any substitute for real butter. Yes, I caved and bought margarine (Smart Balance) for spreading on toast (not that we eat much toast around here), and I use cooking spray occasionally as well. As far as baking and cooking go though, there is no substitute for the real thing. The flavor alone is reason enough but not my only rationale for choosing butter.
I try to live by what I call The Grandma Diet. My grandma (as well as many of yours) grew up on and raised her children on a "country diet" - whole milk, butter, cheese, eggs, and meat as well as fresh and local (usually homegrown) in-season fruits and veggies, of course. All of these were minimally processed, close to the earth and still recognizable as single source foods. I believe this is the way to go. Period.
While many of these good, wholesome items get a bad rap, I frankly am amazed at what does pass for food these days. I'm not exactly sure if margarine (17 ingredients in my Smart Balance), Velveeta (15 ingredients), Twinkies (28 ingredients), and Cool-Whip (14 ingredients) actually count as food, but they sell them at the grocery store.
Now, I don't mean to sound preachy...and, no, I don't exclusively eat from scratch (I happen to ADORE Spam - I buy the light version with half the fat and sodium - that's another topic for another day), but I believe I owe my family's good health to primarily eating foods with minimal ingredient lists containing items that I can both pronounce and would be willing to eat as is (I don't know about you, but I never had any desire to have a sodium stearol lactylate sandwich).
PS - Watch this cool, disgusting, and hysterical Cool-Whip video: http://www.pbs.org/kcet/wiredscience/video/102-cool_whip.html
Oh, and of course, how could I forget. Thanks for the reminder AB: