I agree with several other posters that an hour-long Mass allows for the most people to attend --in our large parishes, six Sunday Masses are said, and if the Masses were longer than an hour, there wouldn’t be time for that many Masses, and not as many people would be able to fit into the nave.
However, what I would say is that if anyone doesn’t get involved with their parish throughout the week in some area–either continued education (e.g. attending the parish Bible study), or charitable outreach (e.g., St. Vincent de Paul), or serving (e.g., teaching religious ed, music, Holy Dusters, etc.)–there might be a problem with that person, and perhaps there’s a good chance that person needs to stop and think whether they actually believe in what the Church teaches or not.
However, we really can’t judge others–everyone’s situation is different, and many people are serving God in their homes, communities (non-church volunteer organizations), or jobs/professions. And many people serve their parish by giving a lot of money, which is very necessary to a healthy parish!
All we can do is examine our own hearts.