There is something mechanical to it. Something artificial. Like its too easy to get into a routine and go through the motion. To value the ritual and the pattern but lose the real meaning behind it.
Does that make sense?
I mean the truth is that in reality all of the above can be said about non-liturgical worship as well. Every non-liturgical church, even the most free flowing, still has a set pattern that they use. Open with prayer, sing songs, take up the offering, preach a sermon, altar call, etc. You can get lost in the motions and lose the meaning. You can value the non-liturgy at the expense of the true reason for worship.
Oh and some would argue that simple is better. That we should keep worship as simple as possible, which makes it easier to keep the focus on God.
That might be a generic answer.
As a Pentecostal, I would respond that a liturgy could stop the Holy Spirit from doing something that he wanted to do. What if he wanted to speak through someone with a word of prophecy?
Or he spontaneously blessed the socks off someone and they couldn’t contain their joy and just started shouting. Then other people just started gettin blessed to and then the whole church just loses itself in God …? In a setting like that, liturgies would be too constricting. I guess Pentecostals value the spontaneity of the Spirit.
Anyway that was what I’d say.
And that’s not to say that I don’t like liturgy. I’ve been to Episcopal churches twice and thought the service was lovely and uplifting. Its not what I’m used to and I enjoy the different atmosphere. Someday I might visit a Catholic service.