Political parties may shift their policies to target the majority of voters, which is probably why they appear so similar. When marketing to the majority, offering something new and different is always fraught with danger as many people only buy into something when its tried and tested. This inhibits political parties from experimenting with the more radical policies that some advocate. Perhaps this is why some senior police officers have been discussing "out of the box" alternatives: a debate on clarifying the paedophilia laws; legalising drugs?
Interactive Democracy allows the more creative policies a chance to be aired, without risk to the political parties. With sufficient support from the public, parliament may be forced to debate them, clarify and present them to the public for ratification, but the politicians can always hold up their hands and say "we are just doing your bidding". It reduces the political risk for them.