Some ways of looking at the Sunday morning worship assembly:
1) Since God is very exacting and demanding in how he wants to be worshipped, it is of utmost importance that we get it right and please him so his wrath does not descend on us. Every Sunday is an exercise in appeasing (pleasing) God.
2) Being a good and faithful Christian means attending each and every Sunday to fulfill the requirements so one stays "saved." Each Sunday is an act of self-preservation through punching a card.
3) Sunday mornings are the time to share God's message with a lost and dying world, so we need an event that communicates in the language and context of 'the lost' so they will be attracted and taught as well. Sunday is a time for attracting seekers on their terms.
4) Sunday mornings are another moment in a lifestyle of following Jesus, neither more or less important, but a significant moment because of the gathering of believers. Sunday is an assembly time for believers that reflects their daily walks and feeds those journeys as well.
I know there are more options, and variations for viewing the Sunday assembly, than just these four, but these will serve to illustrate my thoughts.
I don't like the first because it is worship out of fear and a flawed view of God. I don't agree with the second because it is self-serving and ultimately empty. It has no daily-life dimension.
The third, though popular in many churches today, strips Christian worship of anything distinctly Christian if it is also not culturally popular. It is consumer-oriented worship; pop-culture worship for a pop-culture world (or whatever worship for whatever world).
Of course the fourth option is the one I prefer. Sunday isn't more important than other days, but it is an important event - to get together with others. We don't focus on appeasing God . . . we share in whatever has to do with our faith and our journeys. Because it is not elevated to a more important time than other times, we are free to do whatever is helpful to our daily walks.
Sunday mornings are not a time to please God, nor to please people. No order is arranged to satisfy God, nor is something planned to satisfy people's desires. Our gatherings should be meaningful and speak to our daily experiences - giving us opportunities to reflect on what has happened in our daily lives, and to prepare us for what will happen as we walk daily with Jesus.
The 'evangelistic' dimension comes not in having a very comfortable 'relevant' worship experience which is a vehicle for communicating a 'how to be saved' message, but in speaking boldly and authenically about life as lived in faith. As believers gather to have real conversation about real life and faith, the Good News is inherent in that discussion.
Rather than assemblies stripped of anything unfamiliar to a person unacquainted with Christianity, our assemblies ought to contain testimony to our faith . . . no matter how foreign that might seem to some. I heard the rationale for a new church start-up in the 80's where the celebration of communion was relegated to Sunday night small groups because the Sunday morning assembly wasn't to have anything that might make the unbeliever uncomfortable. The logic is sound if one's goal is consumer-friendly Christianity.
I hope we continue to spend time planning our worship gatherings, not to appease God, not to entertain or attract people, but to deal authenically in whatever way possible with how faith and life in our world intersect. We are free to be rich in Christian meaning and free to be adaptive to ways of communicating with no other goal than to be truthful about how to live in the Kingdom of God.