I just stumbled a simple but missing feature, that "skinparam linetype" can be made straight (just connecting source and target in a simple straight line).
Example which I would like to replicate in PlantUML:
Looking into the source code I found here http://grepcode.com/file_/repo1.maven.org/maven2/net.sourceforge.plantuml/plantuml/8028/net/sourceforge/plantuml/SkinParam.java/?v=source
there does not seem to be such an option yet, neither is it documented anywhere.
Please consider adding it!