Welcome aboard! :D
I do prefer to create my own control files, because I can then tune every little thing that I can to optimise the load. I do sometimes use the bulk load stage to generate a prototype; other times I don't.
If I want to run the bulk loader under DataStage control, I use either ExecSH as an after-job subroutine, or DSExecute from within a custom after-job subroutine.
Bulk loaders generally work best with fixed-width format data; this may be why there's no option to have delimited fields in the data file. If you think this is a deficiency, you can lodge an enhancement request here (there's a dedicated forum for enhancement requests to the products), or on
Ascential Developer Net, or through your support provider.