The efficiency difference between native and "modern" web stuff is easily several orders of magnitude; you can write very useful applications that are only a few KB in size, a single binary, and that same binary will work across 25 years of OS versions.
Yes, computers have gotten faster and memory and disks much larger. That doesn't mean we should be wasting it to do the same or even less functionality we had with the machines of 10 or 20 years ago.
For example, IM, video/audio calls, and working with email shouldn't take hundreds of MB of RAM, a GHz-level many-core processor, and GBs of disk space. All of that was comfortably possible --- simultaneously --- with 256MB of RAM and a single-core 400MHz Pentium II. Even the web stuff at the time was nowhere near as disgusting as it is today --- AJAX was around, websites did use JS, but simple things like webchats still didn't require as much bloat. I lived through that era, so I knew it was possible, but the younger generation hasn't, so perhaps it skews their idea of efficiency.
In terms of improvement, some things are understandable and rational, such as newer video codecs requiring more processing power because they are intrinsically more complex and that complexity is essential to their increase in quality. But other things, like sending a text message or email, most certainly do not. In many ways, software has regressed significantly.