Depends what feel are you trying to achieve, but it's not necessary.

I've been doing some filming this year and decided to use just one lens, 17-50 mm on a 1,6 cropped body. Here's one example https://vimeo.com/51109926

Not at all necessary. I like to shoot wide, but not fisheye. So on a full frame I like to shoot widest around 18mm. It's wide enough to be a follow cam, but doesn't distort much. Downside with shooting standard to long lens is that small tricks look small.

that's pretty damn good! i have a 14-42 on a 2x crop body.

yes, sir!

That's what I did.

a big fat fish eye with an even mix of standard lens or wide angle shots tends to look best aesthetically imo