While it is a person's right to seek knowledge, I have to say that willful ignorance is unacceptable in my opinion. For instance, according to the law, ignorance isn't an excuse to commit a crime. If you commit a crime, like say, taking a car out for a joy ride, and you get caught, you can't tell the arresting officer "oh, i didn't know it was illegal," because it's within your reasoned independence to know the law. Police officers aren't there to teach you the law, they're there to make sure you're upholding it.
It's an individuals responsibility and right to know and to learn.
It makes no sense to tolerate willful ignorance; although it is the person's choice whether or not to pursue knowledge, society should encourage open-mindedness and learning. If we fail to encourage these traits, then we will forever be plagued by arrogance and refusal to change, meaning our progress is hindered.
The word "ignorance" can be a bit ambiguous in this sense.
For instance, I am wilfully ignorant in quantum physics - I knowingly don't study that subject. However, this is obviously not the definition the asker had in mind.
What he did have in mind, I can only assume, is the kind of ignorance that simply dismisses evidence and literally fights for the wrong cause despite all the reasons not to.
That kind of ignorance is not acceptable if our societies try to advance morally and technologically.
In short, it is okay to be ignorant in certain fields but then you should acknowledge your ignorance in said fields as well. Imposing your ignorant ideas on others is not acceptable.
While a society may function under the premise that, in order for people to be happy, we must allot for a general type of happiness, rather than the sort of Platonic rationalism that would awaken them, and allow them to truly be happy, that does not make it any more sensible to allow willful ignorance to be acceptable. It should be the tendency of a society towards rationality and understanding of subjects, rather than to abandon them because one simply chooses not to know about them. It is not about simply being *aware* of these things, but understanding them, and having a position on them, rather than remaining neutral on these subjects based on the idea that that we are ignorant because we may find them unpleasant, or we are afraid of them; it doesn't do a society good to have a number of people who are mathematically illiterate because they have decided that math is not important to them; in today's society, this is detrimental, under the consideration that mathematics is playing a larger and larger role in most every day tasks, even if they are subliminal, a basic understanding of how certain principles work can be beneficial in helping a society achieve greater understanding, and as a result, rationality of it's world around them.