Ginger and turmeric are good staple items to keep in your spice rack, especially if you make Indian food. The idea here, is to always keep stocked, things that many recipes require…so that you never have to buy more than 2 or 3 things to cook most things…Garlic and onion powder, pepper, chili powder, cumin, etc…
Actually, the two ingredients you highlighted as examples are quite strong aromatics and do make a significant difference in terms of flavour and aroma. Not sure about where you live, but fresh ginger is relatively inexpensive and widely available in most major urban centres. Fresh turmeric is less so (often only sold in ethnic grocers), although turmeric powder is likewise relatively inexpensive and widely available in most major urban centres.