I don’t think metaphors and similies are bad, and it would be difficult to write without using some. But if they’re noticable, they probably shouldn’t be there. Many writers try too hard with metaphors and similies, and they come out overblown, contrived, mixed, or flowery.
But goods ones that bring out the truth of a matter, while not going overboard, can make for very good writing. Writing good, meaningful, quiet metaphors and similies is an art form unto itself.
In humor, of course, overblown metaphors and similies can be wonderful. But unintentianally funny ones can be brutal.