One of the frequent criticisms of the original NBN is that we don't need more than 25 mega bits per second. Indeed, the Vertigan Cost Benefit Analysis instgate by Mr. Turnbull declared that the median household (the 50 per cent proportion of households) would require only a bandwidth of 15 Mbps in 2023

This improves a bit on Mr. Turnbull's prediction of October 2010 when Malcolm Turnbull claimed that 12 megabits per second (Mbps) connection to the home is enough for anybody, with no applications existing today that require additional bandwidth:

“For most, if not all applications, much lower speeds are perfectly [fine],” he said. “If you could deliver nationwide 12Mbps at relatively modest cost compared to the NBN, what is the additional utility/value of going from 12 [Mbps] to 100 [Mbps].

In the Coalition's Plan for Fast Broadband and an Afforable NBN of April 2013 they stated:

Our goal is for every household and business to have access to broadband with a download data rate of between 25 and 100 Mbps by late 2016. Downloads average less than five megabits per second at present.

The 25 Mbps promise in the Multi Technology mix plan of 2013 improved again on Mr Turnbulls 12 Mbps. In March 2018 this has still not eventuated. In fact towards the end of 2017 the NBN decided to offer 50 Mbps plans in lieu of the 25 Mbps plan to their Service Providers.

It is true that many tasks on the internet can easily be done today with less than 10 Mbps. Even for those, delays often occurs when other people in your houshold are doing more network intensive work.

Examples of this may be: You are receiving a email with high quality photos, you are waiting for a large PDF file to become available in your browser, you are downloading a new version of Google Street View or a Windows update, etc. These activities often take several minutes and while they happen neither you on your device or anyone else using your connection with different devices can access the internet with reasonable response on a slow network.

In many households now there would often be four or more people engaged in internet activity using computers, tablets, phones, televisions, games consoles etc.

To have two or more such activities simultaneously going will quickly show the need for higher internet connections. If you take into account that the number of devices using the internet in your home is very likely to increase in the future, the need for higher speed becomes clearer. Estimates of up to fifteen devices per household in the not to distant future exist. Many homes currently have six or more. Not all these devices need to be operated by a human, e.g. you may be recording a TV program over the internet on your media system, your house electicity consumption may be monitored or a security system may be active.