The smearing of the FBI is ridiculous and unwarranted, IMO. There's zero basis to conclude they did anything wrong with that particular investigation (and I'm not even defending Hillary here).
They conduct hundreds of investigations in any given year, most of them to the highest standards. They're not perfect and they're not angels, but this idea that they're not competent to carry out investigations is ridiculous.
And yes, it would've avoided the public hearing circus. The FBI conduct their investigations in private, then announce the results publicly.