Hail and well met, all you Thanes and...Thanesses(?)

I have a question regarding Rangers. I have read the tacticas and the Army Book, so I understand the theory of them pretty well, but we all know theory and the real world have so much in common.

Are they truly useless? I rarely see them played or even included in posted lists. Even then, I see more experienced players discouraging their use.

Are they just a neat entry in the Army Book that no one ever uses, similar to half of all the Necron unit types in 40k?

I figure that ten Longbeard Rangers joined by a combat Thane and with a Rune of Stoicism or a Rune of Slowness would make ideal self-supporting advance flankers. Extraordinarily expensive ones, but effective. Add another ten Miners to the list and the Rangers can hold until the Miners arrive. By the time those two units have been dispatched, the bulk of the infantry and artillery has probably arrived, largely unmolested.

It seems like a no-brainer, but I only ever see them in 'theme-y' lists.

Are Rangers better off as mere upgraded Warriors or as Longbeards? Should they carry a magic standard or is that too risky?

Thanks for your advice!