So are you asking for ways that nursing theory is not important? Is that what you mean by "the negative side"? Firstly, nursing theory is very important and provides you with the foundation upon which you will build your nursing knowledge and cultivates your critical thinking. If nursing theory was not important and we were only in nursing school to learn skills then nursing school would only be a month or two long.
Conversely, being that you are "on the negative side", you could argue that while nursing theory IS important there are areas in which the ideal scenarios that are used in the textbook are irrelevant to real world situations. You could argue that the antiquated notion of ideal situations with an ideal patient and ideal docotors and ideal families and ideal co-workers that is prevelant in nursing theory sets students up for severe shell shock when they actually enter the real world of nursing and perhaps makes them less prepared than they would be had they been taught how to (additionally) deal with less than ideal scenarios.