That's a pretty ignorant statement. How long ago was 640k? There are a lot of people that don't even use the full 8 gigs yet. I have a 2 year old gaming desktop that I have to push hard to use the full 8. Unless you are using VMs, doing heavy photoshop, movie editing, CAD and things like that... then you wont need 16 gigs in the next 4-5 years. Software just doesn't double its needs like that.
Engineers are not trying to push the hardware. Using the memory comes from lazy programming. RAM is so cheap that your variables don't matter. There is no need for efficient programming so programmers get lazy.
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That's because you are using VMs. Not everyone does that. Most people that do that don't need to do that either. In fact you don't even need to do that. Run it on bootcamp.
Not to point out the obvious, his first statement was made out of jest.
Also as services become more complex, it should follow that the underlying software use more resources, so it is never wrong to recommend more ram especially since the RMBP is non user upgradeable.
Additionally, I think you've agreed with the quoted poster by saying there are lazy programmers out there, we should always have headroom in our systems so we can compensate for ram guzzlers. Sometimes our workplaces or schools may not cater for other more efficient software and that's where having that extra bit of ram will count.
Lastly, nothing beats the convenience of a VM, bootcamp rearranges your partitions and requires a lengthy reboot. VMs are totally modular and can be transferred from computer to computer without hassle.