Not to be a wet blanket, but yes ignorance should be tolerated and warmly received about things which do not matter much, but sometimes a person's ignorance about certain things can tell you unfortunate truths about the way they view the world and what they consider worth looking into or not.
For example, think of someone who is ignorant of the cultural practices of a certain minority of people despite seeing members of this group every day in their neighborhood, this tells me something not so positive about this person and how they view the world and other people. However it is never too late to change, either.
The same can be said for class as well, many people I have met who have grown up wealthy and comfortable and just don't think much about the people who serve their food, do work for them, make the things they buy, and have no idea who they are and what their lives are like and don't wonder about it. Part of that is how society is structured to hide these people from them, that's part of what they're paying for.
For example, think of someone who is ignorant of the cultural practices of a certain minority of people despite seeing members of this group every day in their neighborhood, this tells me something not so positive about this person and how they view the world and other people. However it is never too late to change, either.