The engineers who design and build the trucks don't agree with you. Why would Dodge or any other manufacturer print bogus weights on their GVWR stickers if the truck is capable of carrying several thousand pounds more weight? How do you know a Ram 2500 and Ram 3500 are identical except for overloads? Is that on spec sheets provided by the manufacturer?
Try getting caught hauling commercially by DOT and tell them the only weights that matter are GCWR and GAWR. You can post that here for those who don't know any better but you'll find it is not accurate if DOT inspects you.
If you are hauling commercially and do not have a Class A CDL the first thing a DOT trooper is going to look at is the GVWR tag on the truck and on the trailer. It is not as simple as your post claims it is.
I have looked at frame part numbers, and they are the same. . its a cost saving measure for DC, just like every truck is wired for just about every option, fewer parts means more profits.
Look at it this way, since the axles and frame are the the same and the main springs are the same (and overloads are all but useless within the confines of GVWR) the 3500 SRW ratings was based on being under the 10K limit to avoid unnecessary weigh station stops. I believe Ford was the first to break 10K on SRW GVWR and Dodge followed, the 2007 3500 SRW went to 10,100 with no hard part changes.
So if you exclude the overloads (mainly because they take over 2500lbs in the bed to contact in a static situation), there are no physical differences in the 2500 and 3500 SRW, yet the 3500 SRW has a 1,100 more in GVWR and 200 lbs more in RAWR. The rating is 100% because a 3500 SRW has to be rated higher than a 2500; its the reason Dodge didn't offer a 3500 SRW for so long, but people wanted it becuase they think its "tougher". I have one because it was the truck I was looking for and I didn't care if it was a 2500 or 3500 SRW.
If GVWR were more important (not saying its not important, just saying its not the most important) then why would you have axle ratings to get you much higher? The front axle on these trucks (QC LB) has about 4,700 lbs on it in an empty truck situation. If you were to load the bed to RAWR you would be at 10,700 lbs, 2,700 lbs over the GVWR.
Like i have said before, if your not comfortable reading between the lines on what hard parts were used then by all means get the truck that has the GVWR you need. If you are comfortable extrapolating the specs then feel free to do so, just make sure your tires can hold it, and your licensed and tagged for your weight.
As for the DOT and GVWR I have asked multiple times and been told GAWR, tires, and tagged GCWR are what they look at. There may be more to it, but thats what I have found on a consistent basis. I also don't haul commercial, and have no plans to, I am referring purely to personal use.
My last jab at OEM ratings... If OEM ratings were the best and most accurate ratings based soley on hard parts then why is my SRW rated to tow more than the same DRW? We know its based on the numbers game, but a DRW is much more capable of heavy towing, but not according to Dodge.