Um, which reminds me...
This priest, (he of the, "I find the Extraordinary Form "offensive," brouhaha,) is asked, he says, "Why it seems that so many Catholics don’t come to the liturgy each Sunday, since the Catechism of the Catholic Church says that 'those who fail in this obligation commit a grave sin.'
Hmmm, I would suggest that one major reason might be that so many priests like him answer such questions so equivocally. "The Catechism does indeed make the obligation clear,... At the same time it is important that we don’t take a statement out of its context."
In other words, it's an obligation -- but not REALLY, (wink wink, nudge, nudge...)
Yes, there are good reasons to miss Mass, and further, I am certainly not advocating checking up on the validity of anyone others' reasons, I got plenty o' sins o' my own to worry about, -- but for virtually my entire life, "oh well, yes, but...", has been the standard answer to concerns or questions about the Sunday "obligation."