This sounds straightforward but you're glossing over a lot of second order effects. Notably, if this idea dominates your attitude you'll be much more likely to miss the cases where a bit of judicious optimization actually would save substantially more in hardware costs. And it may not be 1k of hardware costs, but hundreds of k per year of cloud compute costs, depending on the situation.
But for many companies building such systems (custom line-of-business software is probably still the largest part of software development happening in the world) it's highly probable that if you can "bail your poor decisions out" by just buying RAM, that's is far more efficient than rebuilding parts of software - a saved man-month of engineering can buy a LOT of RAM; a terabyte of it is probably in the range where it's not even particularly worth trying to carefully evaluate the options as a well-staffed meeting or two discussing the possibilities can be more expensive than buying a few RAM sticks more.