You suggest tax cuts as a possible remedy to the economy--it should be noted, that along with direct government spending, tax cuts are one of two canonical Keynesian fiscal stimulus policies. By putting money in the pockets of businesses and consumers, tax cuts increase demand.
Perhaps, instead, you were emphasizing the role of tax cuts in either incentivizing work effort or investment. It does not seem at present, however, that there is a shortage of labor supply--rather, it is firms who are not hiring. And even if business taxes were eliminated--and, for that matter, regulations were relaxed--firms will not invest or expand in a depressed economy.
With regard to your point about wasteful government: It is true that in normal times government spending crowds out the activity of the private sector. However, these times are not normal. In particular, the US economy is stuck in a liquidity trap. This means that at present the Fed Funds rate has been pushed as low as possible—to effectively zero—and that the rate would need to be lower to motivate investors to use the excess savings in the economy (the Fed itself estimates that the market-clearing Fed Funds rate would be negative). The under-use of savings has led to a shortfall in demand, which in turn is depressing the economy. In such conditions, there is a strong case for the government to act as an investor of last resort, as such actions will cause no crowding-out of private sector activity and indeed will increase overall demand.
There is an important distinction between unemployment as a result of inadequate economic stimulus, and the so-called "job-killing machines" you mention.
Economic growth has always been predicated on technological advances, and technological advances inevitably render sectors of the economy outdated. This process does imply a temporary loss of jobs, but in the long run consumers benefit from lower prices and the labor force can flow into more productive fields. This is the "creative destruction" championed by Schumpeter as a defining characteristic of capitalism.
On the other hand, inadequate economic stimulus is a pure loss in the sense that our economy is currently exhibiting a shortfall of demand--the ongoing banking-sector and household deleveraging mentioned by El-Erian are two causes of this. In this situation expansionary policies can provide an unambiguous boost to the economy--there is no broader purpose to the jobs lost from a too-weak stimulus.