There are several issues here. For some form of brevity here:
1. Perth is making that transition from being a small country town to a big country town to being dragged screaming into the 21st century. The town planners may have the plans but as civil servants, they have to do the bidding of their masters who have many other agendas - amongst these, issues like bicycle paths will be a long time coming. I'm quite surprised that Perth's existing bike network is as good as it is.
2. Something happens to athletes when that mixture of second wind, getting past the wall, endorphins, serotonin, sweat and VO2max kick on their bicycles. Add that to the genetically inherent composition of a bunch of them on two wheels and you get a pack mentality who want to emphasis their right under the law. I think the law is that you're allowed to ride two abreast on a road if there's a group. I don't think it's stipulated how big or small this is.
3. I've even seen cyclists intimidated by these packs of cyclists. It only takes one to give the others a bad name. The point is that all this "aggro" doesn't make them any more attractive, only more resented of and begrudged.
4. I do think all motorists should start off or take up cycling. It's only when you're exposed to all that traffic while riding along, do you REALLY appreciate safe driving I think.
5. Cyclists have rights and many are justified in fighting for their rights. Many motorists do give cyclists a hard time and vice versa and before you know it, you get a vicious cycle going. Cyclists may not pay rego, but they are tax payers and they are human beings and are entitled to use the roads.
So... hurry up with those bike paths I say. Look at Holland, it has a world class bicycle network and the cars get along just fine.