COMPUTERS actually don't need more RAM to run well,the OS that runs the comuters You're using needs more RAM to run well.
The huge increase in added software & protection routines & modules to "make it pretty" are what increased the need for resources. And yes, I'm referring to MS Windows. As You'll notice, with each Windows version the requirements increased in large amounts. (Coincidentally, the requirements for Win10 are closer to Win7's than the ones are for Win8.
HOWEVER - Simply by looking into the enormous amount of linux distros You couldpossibly run on Your computer You'll find that more RAM above a very basic 2Gbs is not required to run most of them- in full graphics mode, and with modern interney browsers that handle streaming video & online gaming.
Best example -Puppy linux, designed for systems as low as 1Ghz (or as low as 266Mhz on the Wary Puppy version) with 512Mbs of RAM or more to run best.
If You have older systems like I do [17 at last count, Craigslistaholic] - PLEASE look into Puppy and / or the Distrowatch.com website.