A hygiene factor is something you miss when it's gone, but barely notice when it's there.
Clean sheets at a hotel, for example. The base salary at a job. Your title.
Every time you add one of these factors to consumer or employee expectation, you've signed up for a lifetime of providing that benefit. You've made it more difficult for the competition to keep up. And you've raised the standards for everyone.
They're important, but their presence doesn't motivate people. It's only when they disappear that we think about them.