Why?

Can some one please explain why anyone thought that "When I Survey the Wondrous Cross" needed a chorus? Those 4 verses, by Issac Watts, served just fine for 300 years. Did Chris Tomlin really need to add this bit?

O the wonderful cross, O the wonderful cross
Bids me come and die and find that I may truly live
O the wonderful cross, O the wonderful cross
All who gather here by grace draw near and bless Your name
(from here)

Just wondering.

Update: This dovetails (1 word or two?) nicely with something I read the other day. First a comment from Cosmic Variance: "...Actually [Christian Rock] mostly sucks because the lyrics are so lame." And linked in another comment there, a (partial) explanation of why it is so.