One reason to keep whole spices on hand is to make your own Glühwein. You could buy some generic "mulling" spices, but the taste isn't quite the same as what you would get at the Christkindlmarkt. Have a cup or two of this warm, spicy wine, and let the Gemütlichkeit flow!
Gernot Katzer's Spice Pages are a multi-lingual, multi-ethnic resource for all things spicy. If a recipe has an unheard-of spice, chances are you'll find it listed here, along with translations into 20 major languages, botanical names, photos, links to recipes, and how it is used in various cuisines.
When a cookbook author writes a how-to tome, somewhere in the middle or towards the end, after the importance of measuring properly, there will be a admonition to use only the freshest of herbs and spices, to buy from a reputable spice merchant with high turn-over, and to throw out anything over a year old. Having baked with really fresh spices, I nod my head and say, yes, yes, everything does taste better when the spices are fresh and zingy and don't taste like cardboard.
But throw out anything over a year old? Does your grandmother know you're suggesting that?
I dare anyone to use even the smallest jar of ground cloves in a year.
So, some of the ground spices in my cabinet are five years old. Some of the herbs are even older (and those are stored next to the stove — the horror!). Oh, sure, I'll grind whole spices as needed — but that's only because I'm crazy about baking. No one just getting into baking will keep whole spices and a spice grinder and containers for the ground spices. And where would you put all of it?