There is no law in Kansas which prohibits private businesses from discriminating based on sexual orientation, right? Are there any lawsuits that have been filed against private businesses for doing so? If not, I don't see the utility of this law.
As for whether private businesses should be so-prohibited (and I know that's not what's currently at issue, at least in Kansas), notions of equality need to be balanced with freedom of religion. Like it or not, homosexuality is considered a sin according to widely-held religious beliefs (including beliefs held by a great many black ministers who are justifiably chagrined that this is being compared to racial discrimination). Perhaps that will change over time, and many Christian denominations already take a much more permissive view towards homosexuality, but a business owner who believes homosexuality is a sin is not necessarily a bigot or a kook, and he or she should be free to deny service.