Cover songs are the result of musicians running out of material, so they decide to either do a creative take on an old song or fuck the original into a fiery oblivion of bad music (see Hilary Duff's cover of "My Generation").
When considering cover versions of songs, you have to remember what benefit this has to you. For example, if you are one of those people who feel they need to be right about everything (keeping in mind you visit cracked.com regularly, and so this is almost definitely you), you could use a band YOU like doing a cover of a shitty band your friend likes' song to shame him. For example, imagine you are a fan of New Found Glory and your friend if a fan of Bryan Adams (this is a hypothetical, not even Bryan Adams is a fan of Bryan Adams). Well, New Found Glory actually KILLED (in a good way) Adams's song "Everything I Do". They made it vaguely likable. Essentially, you can tell your friend to fuck off, as Bryan Adams sucks at playing his own fucking songs. This is a big plus for you, as you can now legally kill that person (it says it in a law somewhere).
Also, I'm pretty sure if you then drink your friends dying tears you get a free ticket to Disneyland. So there's that.
First of all there, as there can be some good cover versions of songs. Sadly, there is an abundance of Fucking Terrible cover versions. I can accept that people have different taste in music, but why-oh-fucking why must artists ruin other people's songs? If it was actually good, then maybe I could accept that, but nothing Madonna has ever done is good. Ever. So when she fucks with one of MY favourite songs she should really die.
Another situation that is annoying about cover songs is people not knowing songs are covers. For example, before Johnny Cash died he released a ball-breakingly awesome cover of "Hurt" by Nine Inch Nails. It was the perfect song for his final release, and it was awesome, like you don't even know. If you got a ball of pure fucking beauty, but in music form, this would be it. But anyway, the problem is, no one knows it's a cover. They say "Cash wrote this, NIN should not touch it" when they heard Nine Inch Nails do it. INJUSTICE.
Cover songs can be awesome at times. They may even actually improve on the original, or get the original artist some more fans. However, it's also important to note that stupid-bitch-retard-o-saurus rexes (read "Madonna") should NEVER go near a song that they have not even got a tiny grasp on the meaning of. Her massacre of all things holy is, and this is not an understatement, worse than genocide.
Sure, we could just tell artists to stop making cover songs, but we could also just kill Madonna. That way we still get some good covers, along with Madonna being dead.