Hillary Clinton and the rest of the Clintons have been under intense scrutiny during this election season. She and her husband have been cleared of every single charge that has been lodged against them. If the FBI does launch an investigation, it is likely that they will be cleared again.
Unfortunately, the nature of our political system is based off of power and money no matter which way you spin it. There must be some serious power plays occurring if the FBI is being extra cautious and extra nonchalant about criminal proceedings. It shows that the United States of America is not impervious to the influences of corruption just like anywhere else.
Considering that the FBI has reason to believe that it is possible that the Clinton Foundation has played a part in some wrongdoings, it is within reason for them to want to keep their minds open to the idea of an investigation. They are simply doing their jobs by remaining interested in assessing whether unlawful actions have taken place.
The FBI operates independently when it investigates potential criminal wrongdoing. The agency works hard to remain non-political and avoid having to cave to political pressure. Therefore, if the FBI decides to investigate the Clinton Foundation for potential wrongdoing then it means that the agency has found cause to do so. In short, the FBI is not caving to political pressure just because it might investigate the Clinton Foundation.