What is the relevance of economic growth? Economic policies often mention high economic growth as a desirable path. For example,

&quot;We started to lay a new foundation for stronger, more durable economic growth.&quot;
-- President Obama, Speech in 2013

But also

&quot;Jeb Bush pledged Monday to give the U.S. an economic growth rate of 4 percent a year&quot;
-- Politico

and many others in the USA and abroad (Hollande, Merkel, etc.)
Politicians from different sides seem to agree that economic growth is desired. For example, some of them say that growth helps against misery. Some of them say that higher growth helps a government with paying back their debt.
How does economic growth help the economy and the society? Through which mechanism does that work?
See also How do economies grow?
World population currently is estimated at $7.3$ billion people, while world GDP at $74.5$ trillion USD (nominal). So the global average of per capita GDP currently stands at USD $10,205$, again nominal, not adjusted for purchasing-power-parity. But in any case, this number, although not negligible, it is small enough so that, even if we had absolute global equidistribution, we would hardly be in an "Affluent Society".  

This alone could justify why Growth is still the main economic target of societies all over the world: even if inequality was out of the picture, we will still be far from living really "comfortably".  

Add inequality to the picture, and one realizes that Growth is also seen as something that can help mitigate possible social tensions due to inequality: one accepts the existence of inequality easier, if ones sees his own fortunes getting better (this requires of course that everybody gets something out of Growth, even in unequal shares).