If you expect to frequently take little falls, then long pants and long sleeves and full finger gloves make sense. But there is no reason why you should be falling that much, after the initial wobbly period when you start riding. I bike commute every day and maybe fall down once every five years, if even that. If you take a big fall, a genuine crash, then long pants/sleeves won't make any difference. Choose your clothes for heat, cold, sweating, rain, convenience, visibility.

I ride to/from work in my normal "business casual" work clothes, normally khakis and a short sleeve shirt, with jackets and rain gear as needed. I could change at work but don't want to take the time.