Why does TradingAs.com.au now want you to have a username/PIN?

So that TradingAs.com.au can save your information on your current run through TradingAs.com.au for your possible future use and keep it secure and only available to yourself via the entry of your username/PIN combination.

Why does TradingAs.com.au want your username to be your email address?

First because it is a unique identifier - there can be no duplication of a valid email address.

Secondly, if you lose or forget your PIN, TradingAs.com.au will only be able to refresh your knowledge of it, if you now choose to enter your correct email address. TradingAs.com.au will only communicate to you your forgotten PIN via the email address you now specify. This is a security measure.

Thirdly, so that the initial correspondence from TradingAs.com.au [e.g. the Tax Invoice (and Receipt) and the ASIC Record of Registration of Business Name etc.] will go to this your username email address [which may be important to you in the event that such email address is different from the email address you want subsequent ongoing correspondence from ASIC (e.g. renewal notices) to go to (which email address you will later get to specify separately].