I really hate you had a very difficult time shopping for a mattress, but I can add some advice for comparison shopping to make it a little more simple. If you decided you liked a model at one store then all you need to do is ask for a copy of the specs for that mattress and then go comparison shopping with the spec sheet. The other retailers should be able to show you the same mattress with a different name and different cover if they carry that model. If not they will have something very close or similar. Get Coil type (Pocketed, offset, bonnell, etc..), number of coils, gauge of wire and number of turns in the coil. The lower the number of the guage of wire the thicker the wire and the firmer the coil. The more turns or rotations in the coil the more durable the spring unit. So 6 turns is better than 3 turns. Write down each layer of foam name and foam thickness. So you will be comparing the same types fo foam.
To clear a couple fo things up these types of mattresses and coils have been around for a very long time. The pocketed coil has been in Simmons Beauty Rest Mattresses since 1925. Latex foam mattresses ahve been around since the 1940's, Memory Foam has been around since the 1980's and it isnt any better then any other poly foam that is the same density. What you refer to as genreric foam is what is in most all mattresses.Memory foam is warmer to sleep on for the simple reason it is a temprature sensitive foam and requires body heat to soften the compression ratio of the foam in order to conform to you better. Now the memory foam in most innerspring mattresses arent very temprature sensitive so you wont notice it anyway. Example: Tempurpedic changes compression ratio with every 3 degree change. The memory foam in Sterns & Foster changes compression with every 27 degree change in temprature. Dont fall for the cool memory foam line. If they use something to keep the memory foam cool you might as well just buy something with all HD Foam and no memory foam. Memory foam does cost more becuase of production and it is an open celled foam, but there is no need to pay the extra money if it is being kept cool or layered under layers of other foams.
The mattress thickness has gotten thicker over the years, but have mantained roughly the same for the last 10 years. As for the weight they are considerable lighter then what mattresses used to be unless your getting All foam and they are about the same weight as an old Stearns & Foster or Sealy Posturepedic. Comparing to a 25yr old mattress there is a huge difference in thickness even with a low profile box it is still most likely going ot be taller.
You will easily find many complaints about every product sold and not just mattresses. You cant make everyone happy and not everyone will make the right choice off the bat. The best way to select a good mattress is to go into the store and narrow it down to 2 or 3 mattress comfort levels and spend 10 or more min laying on each one. Ask the sales person let you take some time just laying on them. He showed walk away and give you some space if he doesnt then ask him to leave you alone for a few minutes so you can relax.
Latex push back is a mythical term created by poly foam manufactures. Latex doesnt push back against you any more or less then any other foam. They will all push back with the exact same force and it is determined by gravity

The industry does realize that a very very small percentage of people can not find the right product for themselves. That goes back to "You cant make everyone happy".
There is nothing free in any industry. If the pillows were free you would be able to get them without the purchase of anything. If you have to buy something to get something free then it isnt free. If the problem was with the mattress why would you expect to get a refund on the pillows. It really baffles me how you speak liek it is a bad thing that you have to pay for delivery. Dont you like to get paid when you work? Your entire complaint seems to be revolved around spending money for a product and services. I am sure you like to get paid for any work you do? and you blame the retailers or the S-Brands for the prices. When you should actually look at the oil prices (Poly foams are a petro product), along with the rasing the cost for transporting the products bd materials. The cost of steel as increased dramatically over the last 10 years. The actual increase in mattress prices in the last 10 years is far lower than the increase in the cost of transportation and materials in the last 10 years. You can purchase a good quality King set for around $1100 and a luxury line for around $2500. You can spend far more than that for the all foam products, which will last longer, but if they arent cokmfortable it doesnt really matter.
Mattress shopping really isnt that complicated. You have quilting, Cushioning layers and coil system in an innerspring mattress. To compare the same brands all you have to do is ask for the specs and take that shopping with you and compare specs to specs. For memory foam ask about the density of the foam and how much memory foam is actually in the mattress. The higher the density the better. Most memory foam mattress only have a couple of inches of memory foam and the core High Density Poly Foam and not memory foam. The cheaper models will have lower density foams with very little actual memory foam and the more expensive models will be all to mostly all memory foam with a high density. Low density is 2lbs or less and high density is 5lbs or higher. Latex is a different breed, but you want to see if it is synthetic latex, blended latex, or 100% natural latex(Very very rare)
I wish you the best of luck with you mattress and hope you enjoy it as it sounds like you have purchased a premium line set.