Most trucks, even 2500 and 3500 series, are geared more towards the side of driving down the freeway empty or with light loads. Next time you take a road trip count how many 2500 or 3500 series trucks you see on the road completely empty or with a very small load in the bed or smaller trailer versus something pulling a big trailer. I bet it's at least 10 trucks running at light load for every one with a heavy load. Based on that manufacturers have to choose what they are going to do in regards to gears and will go with how most people use their trucks. The cab chassis trucks which are primarily used for true work and haul heavier loads much more consistently usually get much lower axle gears. You can get 4.44 or 4.89 gears on a Ram 5500, and the factory tires are only 32" tall so not like they have big rig semi tires or something on them. The vast majority of people driving 2500 series trucks don't need, nor do they want, low axle gears to drive back and forth to the mall parking lot and carry home a Starbucks coffee and some bagels......
With that said, if the primary purpose of the truck is to pull a larger trailer then lower axle gears can make it tow a lot nicer. In my opinion lower axle gears are mostly noticed when cruising at speed down the road as they allow you to maintain a higher transmission gear, meaning you actually take advantage of all the gears in the trans. Gears really don't make a huge difference in initial take off because the 1st gear of most modern trans is so low (especially compared to the 1st gear ratio of truck going into the early 2000's). For example my previous 2003 Chevy 2500HD only had a 2.48:1 first gear (that gear range was common across other brands also) with 4.10 axle ratio. My current '16 Ram 2500 has a 3.23:1 first gear along with the same 4.10 axle ratio. That's a pretty big difference in overall 1st gear ratio. The Chevy would have needed a 5.34 axle ratio to equal to overall 1st gear ratio of the Ram. Sure, you can run a lower gear in the trans to compensate for the weight but what is the purpose of having something like an 8 speed trans if you have to run in 5th or 6th gear to maintain speed on the freeway, and then shift down to 3rd or 4th on a grade? Lower axle gears give you the ability to cruise in 7th, or even 8th, gear down the freeway and allows more options for downshifting for grades. Keep in mind that the gear spacing is usually closer together between the higher gears so you don't get into that issue with not being able to pull in a higher gear and downshifting one gear leaves the engine screaming.