It was sure nice of Jack Johnson to write those songs for Jason Mraz, and to clearly advise him that copying the Jack Johnson singing style was also a good idea.

But then, it sure was nice of Ben Harper to hand over a sort of watered-down, infinitely more flimsy and gutless version of the mellower side of his+ style to Jack Johnson - and even to help out by playing slide guitar on Jack's first album, and letting Jack play support slots at some of his shows, back in the days before some record company marketing guy decided that ultra-bland rhyming nonsense from the North Shore was "the soundtrack to +your summer"...
Once upon a time - well, in the year 2000 actually - I saw Jack Johnson and his oh-so-bohemian friends sitting around a fire on the beach at Pipeline, Oahu, in front of his dad's beachfront house, playing his guitar and being all chilled out and hippyish...
"Oh look, there's Jack Johnson," said my mate.
"Who?" said I... "Oh, that guy..." and we walked on up the beach to where we had chained our bikes in the sandy alleyway next to Jack's dad's house...
It all looked like a bit of harmless, slightly self-indulgent fun around that campfire... shame it didn't stay there...

Not a Jack Johnson fan then, Timdog? Remember, you write from the perspective of a world travelling nomadic surfer dude, not a chained down 9-5 mortgage slave like me!
My original post was understated (I am Australian after all).
Whether or not you like him (JJ), I care not. That said, Jason Mraz is flat out copying Johnson even to the point of vocal inflection. Sure Ben Harper helped Johnson, but Johnson was already writing his own music as soundtracks to his music before Harper came along. And, the slide interlude by Harper on the song Flake is cool, but totally different to the rest of the album(s).
I'm not always in the mood for mellow by any means- I'm also a big metal fan- but I loved Jack's first two albums. The next two are sameish no question, and his musical ride may soon be over I think.

Well... I'll grudgingly admit that I did rather like the first two albums, but then Curious George came out and the balance swung rapidly in the other direction. And when I heard the track "banana pancakes" for some reason it prompted an uncharacteristic urge to do physical violence to the person who had created it... I've never really been able to listen to Jack Johnson since...
You're absolutely right about Jason Mraz - that's one of the reasons I wish JJ never left his Hawaiian campfire: the imitators he's spawned. Jack Johnson is light and flimsy enough himself, so the Jack-lite imitators are thinner than air, and curiously offensive by way of their very blandness...