A proven recipe does NOT mean you couldn't benefit from testing/adjusting acid. Grape/fruit acidity varies harvest to harvest and location to location.
pH and acidity are related, but testing/adjusting one is not a substitute for testing adjusting the other. Different wines can/will have different pH with identical acidity. In the same way, the same amount of acidity adjustment in multiple wines will result in different amounts of change in pH.
There are generally accepted ranges of acidity based on wine style, but these are guidelines. Taste is the final test.
When making adjustments to acidity, you need to monitor the effect on pH. pH is what determines microbial stability and effectiveness of a given level of SO2 in protecting the wine. The higher the pH, the higher the level of SO2 required.
You'll never be able to look at a chart and get both TA and pH to be at some exact, theoretical level. You'll make trade-offs -- pH vs taste -- to get the wine where you want it. This is part of the art.
Having said all of that, it is quite possible to follow a proven recipe and get a good wine without making these adjustments. It is almost guaranteed that the result will be different from the original. How much different is the unknown you are minimizing by measuring/adjusting the variables you have control over.
Aging has little direct effect on acidity, but can have an effect on how acidity is perceived. For example, a young wine with a moderate tannin level with taste harsher if the acidity is high. As the wine ages, the tannins will soften and the harshness will diminish. How far it can go via aging depends on the relative levels of tannins & acidity and other constituents that make up the whole of the wine in question. Alcohol is another element that needs to be balanced.
Taken together, the concept of balance involves acidity, sweetness, body, tannins and alcohol. Any one of these that are too far out will impact the perception of the others in a negative way. Aging may improve such a wine, but it will only improve as far as the inherent balance will allow.
How's that for a concise answer to a simple question?