We’re required to keep holy the Lord’s day, which is why the Church states it’s an “obligation.”
An unfortunate choice of words, I think. “Obligation” sounds a lot like “jury duty,” or something equally unappetizing, and just the idea of “having” to be there probably is like waving a red flag at a bull for a lot of people.
If the Catholic Church was more into marketing itself, she would retain the obligatory nature but refer to it as the “Sunday Invitation to Mass,” or something else welcoming, nurturing, and holding forth the joy of participating as a community in the holy Sacrifice of the Mass.
I once saw a mailing from my parish which looked like an engraved invitation that read, “Jesus of Nazareth requests the honor of your presence at a Supper in His honor” and giving the Mass times. It was an incredibly welcoming and eye-catching piece of public relations. I know good Catholics shouldn’t have to rely on such gimmicks, but that weekend it gave me a whole different attitude about getting up and going to Mass!
I’m hoping that the new evangelization wave that is sweeping the Church will use what is good about advertising and marketing to help spread the message of the Gospel and be creative about getting nominal Catholics back to church, and new seekers in the doors.