I find this discussion pretty interesting - as a recent convert to bicycle commuting myself. Here's my two cents:
The way I look at it, to be on the road in any form of vehicle (car, bus, motorbike, truck, tractor, forklift...) you need a licence. Getting that licence requires lots (especially in WA) of time, training, and education. Often this training is specific to the vehicle you wish to use... differing licences for motorbikes, large vehicles etc. Violation of road rules results in penalties, including loss of licence, which go on a permanent record of your road-use behaviour.
To legally ride a bike on the road you need zero training and no licence of any kind. Obviously knowledge of road rules will go a long way to keeping you alive, but theoretically a cyclist could have no idea of road rules... should they be riding on the road? If a cyclist is a menace on the road, besides fines, there is nothing the law can do to stop them from cycling, is there?
I don't have a drivers licence, have never sat for one, probably never will. Should someone like me be on the road? Avoiding the footpaths so I am seen to be playing by the rules and not 'giving cyclists a bad name'?
A roller-blader or skateboarder (with no brakes I might add) is permitted on the footpath.
I try to keep to shared paths as much as possible, but to me the footpath is a far safer and more logical option for areas where the cycle-legal path does not cater. As a pedestrian-cyclist rather than a vehicular one, you are afforded the option of travelling at speeds appropriate to the given situation (not having to keep up speeds of traffic around you to minimise inconvenience to motorists), talking to people on the path, saying 'excuse me' and 'thankyou' in addition to impersonal (and often irritating) belling. It is much easier to be a courteous and concientious cyclist on the footpath than to apologise to motorists in their steel bubbles who are gone again in an eyeblink.
Obviously it's illegal to be on the footpath, but in my eyes I'm more likely to cause an accident on the road than I am on the path going 10 kmh and paying attention. It also pays to pick your timing and your route - footpaths have rush hour too, often corresponding to school proximity.
(edit for clarity)