Sure - needlessly more-or-less entails serving no useful or desired purpose.Would 'needlessly complicated' rather than 'complex' make a difference?
I don't know whether the warlock is needlessly complex. But clearly some of its complexity is the result of mechanical rather than thematic considerations. For instance, the 1x/day invocations are the result of trying to integrate a 1x/short rest spell mechanic with a spell list that is balanced mostly around 1x/day slot availability.