While I guess it’s technically true “you don’t really have to cool it”, it’s better to do so if you can. First, it takes less co2 pressure at lower temps to reach the same carbonation, so you’re using less of your co2. The chart posted shows this. (I have this chart printed and taped inside my kegerator.) Second, homebrew just doesn’t store well at room temp. Its not filtered like commercial beer. The little yeast that may have been carried into the keg can start reproducing again even under pressure, which can at least cloud your beer if not eventually produce off flavors. Any bacteria or contaminants can also get started and get a foothold better at room temp. 25 psi at room temp will be too much when that is cooled to 45 degrees or lower.
That's a load of nonsense:
- if you carb your beer to a certain CO2 content you'll use up the same amount of CO2 no matter what temperature you do it at. The amount required is given by the required increase in CO2 content per unit of volume times the total volume. CO2 doesn't get "used up" and barring any leaks it will all be absorbed by the beer regardless of temperature.
- beer in general ages and stores well at room temperature. There are beer styles that actually benefit from conditioning at temperatures as high as 30°C (think Belgian styles). If you're doing a tradiotional lager then this is not the case but that's a specific case and cannot be generalized.
- yeast will not "start reproducing" just because you raise the temperature as it also needs food (and oxygen BTW) to start doing that. If your beer is fully fermented there is no more food available (hopefully no O2 as well) and so your beer will not cloud up with yeast just because you store it warm.
- if there isn't an inordinate amount of headspace in the keg 25 PSI at room temperature when cooled to a lower temp will stabilize at the pressure corresponding to the same carbonation level. The beer will not remain at 25 PSI and magically become overcarbonated, which is what you seem to be implying.
It's true that infections will progress faster at room temperature but the solution to that is good sanitation practices (i.e. not getting your beer infected in the first place) and not keeping your beer cold so as to slow down infection.
Incidentally, beer absorbs CO2 faster at room temperature so forced carbonation will require less time the higher the temperature is, provided of course you set the regulator to the correspondingly higher pressure, which as already mentioned has zero side effects on the process.
