Because there is really no need for the widgets dojo provides. In every project where a widget kind of thing was required - the requirement also included it to be developed in house, exactly suited to our needs. If we would have chosen dojo widgets we would have had to alter them heavily to do what we want, the way we want it, the way it fits with our codebase. We did that once though, and learned not do try that again.
How is using dojo widgets not "cut and paste"? Thats exactly what cut and paste is, all the jQuery stuff we develop is our own, not cut and pasted. If we really wanted to use dojo widgets, some in the team would have to dig deep into dijit, which makes the whole thing useless since they might as well develop their own "widgets" using jquery in less time, and less maintenence, and less dependency on yet another abstraction/library.
