It's only a matter of time before that kind of RAM size is normal for very low-power and low-cost devices though, and if running Linux makes your development faster or easier or whatever then it's good to have it as an option.

It really depends on the application, how much processing power you need, etc. but more options are only a good thing.

Remember that the 'T' in IoT doesn't just mean little things - these guys are talking about devices that monitor large transformers and power distribution equipment (critical electrical infrastructure). It's likely that an IoT device for that would be doing a lot more than, say, a smart meter for a home for which Linux probably would be overkill.