I’m not going to pretend to have read this entire thread, it I’ve skimmed enough to have gotten the gist of things. To the OP, as others have said, it’s a precept of the Church. Period. I don’t know where you are, but in most dioceses of the United States, there are only five of these during the course of the year. Of those five, one is Christmas, when everyone goes to Mass anyway. In most years, some will fall on a Sunday place the regular Sunday liturgy for that week, or fall on a Saturday or Monday and be abrogated (excepting the Solemnity of the Immaculate Conception). Even if it happens that someone HAS to go to Mass five times over the course of the year in addition to Sunday, we’re talking 57 hours out of 8,760 hours in a year. That seems relatively minor.
If someone were to, sadly, choose to forfeit his or her salvation over “only” blowing off Mass on the Solemnity of Mary, the Mother of God, such a person would be choosing eternal separation from God because he or she has essentially the same attitude as the fallen angels, “My will be done.” The bigger issue here isn’t missing Mass, per se, it’s the underlying attitude of such a person. “I don’t feel like going, so I’m not going.” In a word, tough. Be an adult! There are plenty of things we all have to do everyday that we don’t like. That’s life. I don’t like going to the dentist. Still need to do it. I don’t like paying taxes. Try that excuse with the IRS on April 15, “I just didn’t feel like submitting a return this year. Sorry.”
But let’s talk about the fallen angels for a moment. You know who are the most legalistic beings in God’s creation? Demons. Yup. Demons. They know the rules of the Church far better than any cannonist in his wildest dreams. It drives me nuts when Catholics just say, “These are the rules. Follow em.” We don’t go to heaven because we followed rules. We go to heaven because we follow a Person, who desires to begin heaven in us here on earth, every time we go to Mass. Frankly, if we have the opportunity, there’s no reason every Catholic shouldn’t be at Mass daily, let alone five extra times over the course of a year. It’s not about the rules…it’s about the relationship with the Person of Jesus Christ. That relationship is mediated in and through the Church which He established.