DCM Original?  

Original ?
Yes.
Ruined by being through-bolted (one of them sadly crooked) ? Also yes.
Please don't ask what you could do to repair them; there are no good solutions.
The purpose of drilled Eames chairs is to give the poor a chance to own an (almost) original icon. DON'T PAY even half of what they would be worth in good condition . . .

If obtained for the appropria...
If obtained for the appropriate price, these chairs could be viewed as an upholstering opportunity, providing one could acquire access to an upholsterer who could perform the work suitably.
SDR- While I don't disagree with your appraisal of these chairs, your suggestion that they are now only suited for "the poor" seems a bit "let them eat cake", which is not very cool!

value
wow! Thanks for the idea and I love that re-work, do you have an idea what that might cost? These are about $100 per chair and since they are already not original, it could be a good opportunity to do something like this.

That red upholstered chair...
That red upholstered chair in the photo has been selling for 400-500 on ebay. I'd guess that after you buy fabric, the foam/labor for the pads will cost something like 70-90 bucks a seat, and probably about the same for the back. This might be negotiated, but good work tends to cost money. The pads can just be attached with bolts, as they're already drilled through. Still, it hurts to think about drilling through the seats...
Too many chairs lost to shoddy repair. (wipes tear from eye)
But rebirth! Rebirth it could be!
(release flock of doves, cue organ and children's choir)

Of course, you're also missin...
Of course, you're also missing all your glides, which sucks. $100 is too much for me. And don't drill through the seats, you'll feel it.

Face it --
they're shot. Look elsewhere. Don't give in to Collector's Disease ("I must have it -- NOW -- before somebody else does !").
Somebody else: get them for parts.

kpc, I would recommend NOT...
kpc, I would recommend NOT buying those chairs or any Eames products for that matter. Sure, Eames chairs look great, but they are poorly designed. The designs are greatly overrated.
Any furniture design that needs to have shock mounts reglued, replaced, or supports that need to be drilled and bolted within the first 40 years of its lifespan is NOT A GOOD DESIGN! Reasearch other designers of the period from American or Europe. You can can find better quality pieces that are just as collectable, beautiful but that are actually usable.

Some things require eventual...
Some things require eventual maintenance, that's the way it goes. I think the DCM chairs in particular last significantly longer with more careful use and smaller-size users.

The Eames
DCW, DCM, LCW, and LCM are so perfectly formed, and so comfortable, that they rightly became instant classics upon introduction, and remain so today. As such, they are worth almost any necessary (if unfortunate) repair and maintenance.
I agree with the concept that proper design includes correct material and manufacturing specification. I think this particular case is comparable to Wright's leaking roofs: The design is so worthy, that one must look the other way (and cough politely, perhaps) when the subject of inherent flaw is raised. In Wright's case, one-piece membrane roofs hadn't been developed for use when he was building his flat-top Usonians; in the Eames case, modern synthetics were still under development in 1946 and are still being improved.
So (in my opinion) we have to be a bit indulgent . . . except when some ignoramus drills holes in the back or seat !
(The crooked seat-back visible in the first photo really adds insult to injury, doesn't it . . .)

.

Clearly
not all objects are worthy of worship.
At least they put the backs on right-side-up, SDR.

Ah...
I think you've maybe mixed the idioms "let them eat cake" and "have ones cake and eat it too" with your irrelevant quasi-offensive photograph, but whatever.
The chairs could still be made to be worship-able, though this would require creativity and work, and money. And a couple yards of vintage Jacob's Coat.
Upholstery is still a potentially great option to uniquely salvage otherwise ruined DCMs, given a low price on the chairs and access to the resources needed to make it happen.

Upholstering does sound...
Upholstering does sound interesting. I'm wondering, would you turn the four bolted chairs into two upholstered chairs? I ask, because as the picture shows, the new upholstered chairs have the fabric applied in a way that is different from the vintage chairs that I've seen. That way, you could use one panel as a backing for the fabric.

compound curves
Any random compound curve doesn't usually fit right on top of itself very well. In this case it will sit too far forward. Maybe it is easier to deal with that problem than to build a better fitting form to attach the upholstery to, but it certainly isn't ideal.
I wouldn't take these chair for more than free.