Grandpa's stamp of approval?

On Facebook, I follow a lot of folks from in and around the Reformed tradition. Some of them have stepped into the waters Anglicanism, following the issues around Federal Vision and whatnot. Recently, I saw the following on a Facebook post, " A good way to test whether your worship music is keeping the 5th commandment: would your grandpa know any of it?"

Now, I understand the argument that our worship music, and the rest of our worship, should be appropriate. What I don't get is the disdain for and ridicule of development and innovation. What seems to be advocated here is a chronological standard on music. If it isn't music (lyrics are not distinguished - so the poster must include tune, instrumentation, etc.) your grandpa would know then you are in danger of violating the 5th commandment.

Was the canon of music sealed along with that of Scripture? If so, where is the sheet music? I know no one who would suggest such a thing. There are those who insist that the Psalms are the only songs worthy of singing in public worship. But then these same individuals typically use music to accompany the Psalms that was written in the 16th and 17th centuries. How did this music get the "grandpa" stamp of approval?

As an aside - those who insist on singing the Psalms don't sing them as found in the Old Covenant text, but as reworded and rethought with references to the church and Christ.

Indeed, how does anything get the "grandpa" seal of approval? One quick glance at history will show the elders typically resist any change or innovation to the status quo.

Imagine if we applied this same 5th commandment test to a host of other issues. How about agriculture? If we applied this test rigorously we would not have any machines for agriculture because the medieval world seriously resisted the industrial revolution. How about science? We all know how strenuously the "grandpa's" of the world reacted to the learning of Copernicus, Galileo, Brahe, and Kepler.

Now I understand that all this begs the question of how we should think about and allow innovation. I don't have a good answer for this, which I'm sure seriously violates the "grandpa" principle. I'm just being a troublemaker. I'm pointing out the flaws in another system without proposing any alternatives or even endorsing an existing alternative. I have no rebuttal for this, as it is completely true.
I'm hoping that I'm not the only one thinking this way and that I'm not the only one turning this over in his mind. Maybe with a few of us carefully dissecting the issue, we can come to a thoughtful response.