Tools are to make your life easier. In BPEL programming tooling is very important, as BPEL can be categorized as a visual programming language, thouhg there’s no such standard on visual notations like in BPMN.
Recently I used Carbon studio on Eclipse Galelio which made it very much easy to model a workflow and generate the BPEL for it. Things like schema processing/visualization for variable types, helps a lot in manipulating them and to avoid alot of selectionFailuers which are the most common errors I encounter in running a BPEL on BPS.
And things like BPEL exporter, saves a lot of time in deploying a process archive and test it.