Tongue “bite” is a response to smoke with a higher pH (more alkaline) than the mouth and tongue are used to. Some tobaccos, notably burleys, contain a high percentage of nitrogenous compounds, and produce a more alkaline smoke. The dreaded “burley curse” often results. Tobacco producers will work to mitigate this by adding sugars to the casing sauces. Sugars, when burned, actually acidify the smoke, resulting in less “bite.” Virginia tobaccos are often blended with burleys to perform the same function.
Body chemistry also seems to play a significant role. The same tobaccos that will cause one person significant distress can be a source of bliss to another. And, our mouth's environmental factors change over time, and react to things like what we eat and what we drink. Unfortunately, it's not simple. I've never known a tobacco that "never bit" 100% of the people 100% of the time.
And, worse, we have to add the pipe into the equation. I've actually had pipes that would turn the most mild-mannered tobaccos into flamethower fuel. Tobaccos that are reliably comfortable for me have been rendered into pain-inducing tinder. Add differences in smoking technique, and the complexity of the system is magnified to the point of intractibility. But, it's not the sugar in Virginias that cause the bite.