A sixties tribute act? She brought sass and suss to the table, adding a twist not simply regurgitation.
And at what point does paying tribute or being influenced become plagiarism?
For me she was a special artist, and as someone who grew up listening to Motown, I can't grasp how you believe she hoodwinked anyone, or that "ignorant" rock journalists were in any way unaware of Tamla or Phil Spector or any of her influences.
She was a great live act. It's a shame that many rate her based on her admittedly shambolic performances in the final two years or so.
I am not a massive fan myself but can see her appeal and don't think it's fair to dismiss her as lightly as you seem to do. I think time will show her in the pantheon mentioned in the article (Dusty etc).
Motown records are there to be played and reactivated, the fact is a fresh face and a fresh approach is often needed. Sure, the original is still the greatest, but that doesn't make her and her ilk tribute acts as I see it..