Why do nursery rhymes have to be so brutal?

Was having a nice dinner conversation with my Mom and my brother the other day and were talking about the songs she used to sing to us... Unconventional and barely heard of songs like 'Three little fishies' (http://www.youtube.com/watch?v=sz22dv90_mY) and 'A froggy would a-wooing go' (http://www.kididdles.com/lyrics/f024.html). Then we went on to nursery rhymes... Now this is scary... I'm sure we're not the only ones who've realized this but have you ever wondered why they are almost always brutal and completely unadvisable for children?

"Ladybug, Ladybug,

Fly away home.

Your house is on fire and your children will burn"

"Humpty Dumpty sat on a wall.

Humpty Dumpty had a great fall.

And all the Kings horses and and all the Kings men,

Couldn't put Humpty together again."

Ok this one really gives me the creeps...

"Three blind mice... Three blind mice...

See how they run... See how they run...

They all ran after the farmer's wife,

Who cut their tails off with a carving knife,

Have you ever seen such a sight in your life?

As Three blind mice.

"Jack and Jill went up the hill to fetch a pail of water.

Jack fell down and broke his crown and Jill came tumbling after!"

-Where's the bloody 'moral' in that???-

... Oh... And don't get me started on 'Rock-a-bye-baby'.

Why... WHY... Would anyone wanna 'rock a baby' on a tree top?

There's more. Oh... You can bet on Humpty's mangled remains there's more...

But I won't go into that so you guys can have a little fun yourselves. Please... If you come across one that's NOT evil and brutal... Post it up on my 'comments', will 'ya?

And we wonder why our Mommy never sang us those rhymes...