Possibly that you are getting older and maybe your senses of smell and taste have dropped to some degree (I'm not being funny here - mine have). Possibly it's the garlic you use maybe it's mass grown commercial stuff grown for quantity rather than taste.

Sometimes the differences between supermarket stuff and homegrown/local produce can be remarkable. We harvested our own garlic last month and I can assure you it is both tasty and that I can smell it. Probably the biggest one on taste I have noticed recently was the comparision between or own home grown Charlottes (which are worth going for even if your only option is a supermarket) and one supermarket's new potatoes.