Cooling the whole case down isn't effective - there are only a couple components inside the case that need direct cooling. Modern fluid cooling systems use plates that attach directly to these components - CPU, RAM, GPU, and the hard drives.

Fluid sounds like a bad mixture with electronics, and why have moving parts that will burn out. And to me, cool air is an appreciated commodity.

To be realtively consumer friendly, an cheap to manufacture, big heatsinks and fans are the way to go.

For higher end professional or hobbyist systems liguid or heat-pump systems could be used to pull heat from the computer.

Keep in mind, you cannot "create" cool, (which is inherently a lack of heat energy), just move the heat from where you don't want it to somewhere you do.

The highest performing cooling systems available are liquid cooled. "Liquid" doesn't necessarily mean water-based.

With the high airflow through a computer case, cooled sidewalls don't do anything. You will cool the air leaving the computer, but that air won't be hitting the very hot components directly.

It seems to me that with ever increasing component sizes, more cooling capability would be desired. Liquid cooling devices are effective yet also take certain degree of maintenance. It seems that a cooling plate may even be shaped as a smaller variation of a heat sink to to save room and may be easier to use a liquid syst.

Liquid cooling, in the tradionial sense of a glycol system, isn't really consumer friendly. Now, phase change heat pipe systems are done mass market systems, to remove heat from specific components to passive or fan-forced radiators.