Yes, it is not a good idea. Animals with whiskers use them to feel. Rodents, like guinea pigs, use them to see if they will fit in a certain area they may not be able to see well, like a tunnel. The whiskers are about the same width as their body.
I did that to my cat once when I was a kid because I thought they were too long and she couldn't even walk straight and she kept on bumping into things, but I guess thats because I cut them down to like 1/8 of an inch. I must say that it looked kinda funny, but I learned never to do that again, especially with a cat that has a vision problem like ours did. Thankfully they grew back in and she was back to her normal self.