It's only because I have got used to using another flight planning software system (PFPS/FalconView) which has this functionality. On some occasions I want to follow a long line feature which is highly serpentine in plan form (for example the Murchison River in Western Australia or the A13 between Austria and Italy). In both of these cases it is not possible to fly straight line at planned altitude without putting in plenty of turns to avoid terrain either side of the line feature. The straight line calculation doesn't fully do justice to the fuel used when following this sort of line feature, and will indicate that less fuel has been used than is actually the case. With PFPS you can remove lines from the PLOG, whilst retaining the fuel calculations. With FalconView you can 'snap to' line features (eg rivers or VFR mandatory routes). I wonder if people following the London Helilanes might find this advantageous too?