You could say
It's valuable because:
It allows us to discover trends over time e.g sales figures, price changes and consumer behaviour as it makes use of historical data,etc.
This could be used to forecast future sales or future values
This could then help the business reduce costs e.g if the business has found that they don't experience a lot of sales during winter months as seen with ice-cream business, they would be able to better manage resources e.g reduce stock or other businesses could lease their extra premises or reduce staff for that time period to avoid wage costs.
How you apply it depends on the context of the question.
It's not so valuable because:
It only accounts for numerical data which isn't effective enough to predict future values.
Qualitative data also has to be adopted to aid a more reliable prediction e.g. research reports on consumer behaviour and tastes and preference
Mistakes are bound to made which reduces accuracy and could be a big problem for the business if they take actions based on such predictions- could lead to loss effectively.
4-point moving averages are less reliable since bigger values could skew the data
Past performance doesn't guarantee the future- external factors such as new competitors and substitutes, legislation and inflation and they are time consuming.
So that's how you would answer it, a pro of why it's valuable and a con showing why it isn't. You could pick a point or 2 from the above and develop them in each paragraph and use another for possible evaluation/judgement