Even assuming it would be possible to build ram that takes almost no power(which is a scarce resource in many systems), still memory is the biggest tool vendors use today to differentiate prices between chips and to optimize profitability and this fits with product makers since more memory generally means more complex and expensive product.

but we also see a shift towards low-cost chips with lots of memory,for example a new NXP dual-core $2 chip with 108k ram .

What's extra nice about this chip is that it let's you use( in theory ) a garbage collected language ,or even a scripting language in one core and c in another core for your realtime stuff,thus enabling you to mostly write high level code while still having a realtime system.