Couple different things involved...
I'm hoping that everyone involved in working on a 40 year old, carbureted, non-airbag car, is working on it as a hobby, and not trying to keep it going as a daily driver so that they can get to and from their 40-plus-hour-a-week job.
If we're in a post apocalyptic world, the nuclear bomb goes off in ten minutes, the zombie horde is banging on the side of the barn, and the only plan of escape is to stick the last car on earth back together with rubber glue, it's a brilliant idea.
But if this is a car "restoration", that kind of implies that there is no emergency for time, and that there is an acceptance that it is going to cost more to do it right. Otherwise, there is no point, and at best, we all end up with something that looks (and works) like a tuck-tuck.
There are some people spending serious money on appearance stuff. I would hope that the same level of importance is placed on the things that hold the car up and make it move under its own power, because those really are important aspects of an auto-mobile.
If this were a car that you could go into the store and buy everything off the shelf, and the question was "buy aftermarket bushings or a tube of window weld?", I doubt there would even be a moment of hesitation before buying the bushings. If the manufactured product was not more desirable, there would be no companies making bushings. By the way, Energy Suspension covers classic American cars thoroughly, but offers much less for Japanese FWD, which is why there are all the little specialists like HaSport, Z1Motorsports, etc., to fill in specific, lower demand applications.
Look around at message boards for common cars where someone asks about window weld, or even the comparison of engine mount inserts to complete engine mount bushing replacement. Plenty of comments about the window weld and inserts being junk or not worth it, and plenty of comments about "that rear one is a pain to replace, if you're going to do it, you might as well do it right".
So we get past the which-is-better question, the only question left is "how much is it worth to do the job right?".
And don't forget that Sportscar-S.Jp has NOS bushings with replacement service:
http://www.sportscar-s.jp/index.php?pag ... 1&Itemid=2
Yes, 40 year old bushings are probably dry rotted and hazardous. But they don't build things like they used to. Between the environmental concerns and the safety concerns, there are methods and materials that can no longer be used in manufacturing, and we end up with a lot of products that last and remain functional for a much shorter time than they did 20, 50, or 100 years ago.
A single-part rubber glue is not going to be the same as a 2+ part catalyst mix done in a manufacturing setting.
Gluing windows into a frame is really not going to have the same stress as attaching a lever arm to a car. The window is going to see forces applied to the skin and carried to the edge in all directions. A lever arm is going to be glued on one end, and all of the length of the arm is leverage to apply force to the glued part. The force is multiplied by how far it is from the pivot, and that small pivot point takes all of the force at one spot.
The deflection of the original rubber bushings is part of the suspension design. The bushing acts as part of the spring and provides part of the resistance to movement of the suspension arm. That is why the shop manual gives instructions to torque the arms after the car is resting on the suspension. And they select different rubber compounds to change the ride quality and handling, which is why the special tuned versions of cars often have different bushings.
The thing to think about is someone does an A-Team/MacGuiver repair on their car. It seems to work fine. They become confident in it and forget about it. They are out driving around, enjoying pushing the car hard, then one bushing gives, that increases the stress on the other three on that corner past their limit, and they give. In a matter of seconds, the car goes from apparently perfect order, to the exact same situation as the 40+ year old bushings that leave the suspension arm hanging loose. And in a few more seconds, the car is in the ditch and we have one less Bellett in this world.
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it flows very smooth and you would need to fill it from above like a cup. Not from the side. 
If I could afford to, I'd be happy to join JT in his endeavor to manufacture a bushing kit for these cars. Being that he has obviously done the research to complete said endeavor, I have to assume he probably knows what he's talking about. But I will say this, these cars were made 50 years ago. Some people are driving on those 50 year old "precision made" factory bushings. And short of solid aluminum, any bushing will have some amount of deflection under a load. Perfect alignment and control arm travel is great on paper, and then your 165/80/13's start rolling on their sides