Let's be honest, the LTV is a bunch of crock. It was a good rhetorical device to rally for a greater power of labor at the turn of the century - the common sense wisdom "he who pays the piper, calls the tune" dressed up in econo-babble to make it look scientific and important - but as science it is a bunch of crock that has zero explanatory power (as most economic theories do anyway.) A scientific theory has a value only if it can predict novel or unknown fact - hindsight rationalizations won't do, since religion does that too (i.e. it is a matter of faith and semantics rather than empirical verification.) The LTV fails to explain the behavior of business firms - from geographic distribution, to structural forms businesses take, to business decision making, to the role of the state in the economy (Keynesianism), to product diversification, to the rise of service economy at the expense of production.
If the use value does not matter, then why do we have such a diversity of products? If the only thing that matters for the capitalist, why does he/she take a considerable risk of developing new products i.e. why is he/she risking the 'exchange value' for creating new "use value?" And how about joint stock companies that separate ownership and business decision making. Do "capitalists" (stock holders) also care only about exchange value? And if so, how do they make the management who are de facto *employees* but who are also the decision makers to care only about exchange value which they fork over to the capitalists? And how about employee-owned stock corporations, are their owners capitalists who care only about exchange value and exploit themselves as workers? And then, there is pesky automation. Today, great value is produced by automated production line with minimal human involvement and with future technological advances it is likely that most material production will be carried by robots controlled by a handful of software engineers. That clearly contradicts the basic premise of the LTV that only human labor produces value. Moreover, with such automated production the profits are made not in manufacturing but distribution - a fundamental fact of life in modern economy on which the LTV has nothing to say.
Methinks that the LTV should be put to rest in the museum of human thought. It was a clever rhetorical device to mobilize support for labor struggle for power in labor-intensive industry era where labor had virtually no decision making power. It spoke to the common sense that those who make it should also have something to say about it, but it had much more gravitas than folk wisdom by adopting economic jargon (which is, btw, what economists do all the time). It is, in a way, like those charismatic revolutionary leaders who do a great job by mobilizing people and making the revolution happen, but after the revolution they should retire because they are likely to run the economy aground.
Wojtek