This may be hard to be fathom, but in the mid-1970s, It's a Wonderful Life was not yet considered an unimpeachable holiday classic, but was instead a somewhat obscure financial flop which had just entered the public domain. Its television ubiquity was yet to be.
This is why the public didn't give two figs that the 1977 TV movie It Happened One Christmas starring Marlo Thomas (kids, ask your grandparents) was a brazen, sometimes shot-by-shot remake: because nobody really knew, or cared, about the original.
Besides, there was no Twitter or blogosphere yet. How were they going to express their righteous anger? On their CB radios? Anyway, I'm going to assume you know Life by heart. If you don't, I kinda envy you.