Maybe, but consider this...I would have had a lot more confidence in Moses on the day of departure if I had witnessed all of plagues and works God had wrought. The Red Sea would have sealed the deal for me. Then I could have made that long hike.
Yeah, you'd think, wouldn't you? Yet all those who asked Aaron to cast a calf of gold and then held an orgy of worship to it were witnesses to all of G-d's wonders. They knew because they had seen, yet they still doubted the moment the wonders stopped.
People are fickle. There's no two ways about it. And our faithlessness is not cured by G-d's miracles.
Shalom.