Peter Williams on Yahoo! Pipes' lack of a text representation:
Almost immediately i was disappointed in the lack of a textual representation of the data extraction and transformation rules that comprise a “pipe”. Being a programmer by trade i always feel happier when i can use my favorite text editor, not to mention source control, for tasks like these. [...] However, my wife, an ETL expert, assured me that visual editing is the norm for tools such as Pipes.
I saw this coming up again and again recently: While for many models (and programs, and anything in between) having a visual representation is nice when you want to read (or view) it, visual authoring sucks in the vast majority of cases. Sadly, being able to efficiently edit something in a text editor, with versioning and diff support and so on is in general not what impresses those who make purchasing decisions.