It is a cartridge design issue.
I just don't hear of steel case issues with SKS's or AK47's, and that is because when the Soviets were designing the cartridge, they took into account different case materials. They expected to use steel. The 7.62 X39 was a well developed round, so the pressure curve, case hardness, case taper, primer composition, rim thickness, etc, were all studied in depth, trade off's made, and what came out was a highly tested and reliable round. An intensive and expensive development period pays off later. The AK47 and its round are well engineering and function well with brass and steel cases.
The .223 round was a wild cat. From what I have found on the web it is simply a round developed by a couple of guys at Bob Hutton's ranch in CA. They wildcatted the .222 Remington round to reach a certain velocity (I think it was 3250 fps) with a certain bullet weight.
Stoner adopted it, but he had no time or money to either wring out his rifle design or the cartridge.
It went into inventory as a commercial off the shelf item. It is what it is.
You can read about all the problems the military had, in defining the .223 round, in the referenced appendix 4.
http://www.dtic.mil/dtic/index.html
Report of the M16 Review Panel Appendix 4 Appendix 4 Ammunition Development Program.
Report of the M16 Rifle Review Panel Volume 7 Appendix 6 review and analysis of M16 System Reliability.
Report of the M16 Review Panel Appendix 5 Procurement
Report of the M16 Review Panel Appendix 7 Vietnam Surveys
Report of the M16 Panel appendix 10 the small arms program
Report of the M16 Review Panel Summary Report.
So what you are seeing is the fallout of a round and rifle that were never designed or developed to use steel as a case material. It was not a consideration. The .223 was just a wild cat developed by a couple of guys, the rifle and the round got into military inventory, and they are what they are.