The value of Data could easily outstrip the value which oil has enjoyed for centuries. However it cannot be quantified in the same way:
|Infinite resource||Finite resource|
|Does not have globally accepted value||Globally accepted value|
|A palpable, quantifiable product|
|Can be sold and re-sold for profit||Can be sold and re-sold for profit|
|Has arbitrary value,
Treated as a spoil of cyber-crime
|Subject to price fluctuations|
|Supply dependent on ability to generate, process and secure||Supply dependent on ability to source and process|
|Ability to generate revenue is not consistent||Consistent ability to generate revenue|
|Not a literal currency, conversely a cornerstone of crypto-currency||Not a literal currency|
Even still in 2019, oil's power is dependent on who can extract it from the ground (and other earthly politics!).
Similarly, the power of data is dependent on electricity and technology and how it is sourced, used and stored. However, if there's an issue or breach of data the consequences are expansive.
However, it being a legal requirement isn't a full-bodied answer to the question of why it's important.
The real answer is that the data your business touches, whether it's client data or company data, is worth money.It has value to all stakeholders involved with your business, to your clients and external forces like the Government or hackers who would poach it.
Your business may not be the Department of Defence, but you do need to be conscious of data security even though you aren't getting hit with tens of thousands of attempted hacks everyday. One is enough to do substantial damage.
How you manage your data is worth money; these processes are particularly valuable to regulatory authorities (the Government, the Office of the Australian Information Commissioner [OAIC] ) and your bottom-line conscious stakeholders - Boards, CEOs and MDs.