Worm Theology?

At the recent Carey Conference there was some discussion of what is sometimes called worm theology. The subject was raised in part by Bob Letham who, in passing, mentioned a hymn he found objectionable that says we are nothing and God is all. Then at some point we sang Hymn 411 from Praise! Isaac Watts' Alas and did my Saviour bleed, where they have altered the striking line Would he devote that sacred head for such a worm as I? to the innocuous Would he devote that sacred head for such a one as I? I asked Dr Letham about this and he said he simply wanted to underline that as Calvinists we are not saying man is worthless.
If you Google the phrase 'worm theology' you get several references. An interesting wikipedia article suggests Watts' hymn is the source of the phrase but also cites the 3 relevant Scripture references Mentioned below and mentions Calvin, Wesley, etc. It comes out against worm theology. A more positive presentation can be found here. One blogger last year noted that the phrase is often just a derogatory term for Calvinism in general and total depravity in particular. She also points out that those who are into self-esteem are its fiercest opponents. She found a Lutheran Missouri Synod article bemoaning the removal of statements referencing 'the 'corrupted-nature' language of Luther and the Formula of Concord' from new Lutheran liturgy.
As she says

'Whatever you think of worm theology, you can't get around the fact that the Bible itself uses the image of a worm in reference to human beings in several places, for instance Job 25:4-6, Isa 41:14 and Ps 22:6. The image isn't used to deny our value as beings made in God's image, but rather to show that in comparison to God, who is righteous, perfect, eternal, and all-powerful, etc, we are like insignificant worms.'
I know the compilers of Praise! are good Calvinists and would defend their omission of the word worm but it is a shame as Watts surely drew the word straight from the Bible. May be this is one more instance where biblical ignorance is letting people down.