Major changes that happen gradually are incredibly hard to notice if you aren't expecting them, and even if you did notice you might just think it's because you got over a cold or spring is here or similar.
Or many ex-smokers were expecting them so did notice the change. I can't tell if you just think the poster should have qualified that not every smoker notices it or if you think it doesn't exist because you didn't notice it.
Think about how the smell longer on your clothes. That smell lingering in your mouth is going to mess with your smell and taste. And that's ignoring the damage inhaling burning air does to your mouth.