Agree, and that's a reasonable point.
However - and this is a *huge* however... the way qantas is dealing with flights converted into vouchers or credits is that when you come to use them, you must buy a fare of equal or higher value. If you have purchased a $1500 fare to London which is now a credit, and when you come to fly they are offering $1200... you won't be able to book that. You'll have to book another fare, which could be $2000. Also, you cannot take your $1500 voucher and use it for three trips to new zealand, or for Aussie domestic.
It gets worse for those that may have purchased a business saver fare to the USA or London for $5999. When you come to redeem that credit it could be the fare is $8999 (which we are seeing some anecdotal evidence of already).
Other airlines like British Airways have converted flights into credit, but allow the passenger to use the credit in any way they want. When they come to redeem the credit, if the fare is lower, they get a new voucher for the balance. And so on, until the total credit is exhausted.
There were so many ways that Qantas could have done this to make the refund conditions fair and reasonable, but they don't seem to have given passengers any choice except to demand a cash refund