I just realized something - this thread has been all over the place trying to answer the first question, and hasn't even touched the second: Do we really need truth?
I propose that while we may not need (or possibly be able to achieve) TRUTHTM, we at least need Truth, if only to have a common frame of reference to converse in. If we're wandering around on the surface of the Earth, it's fine to stick with the 'truth' that the Earth is flat - until we have to fly from DC to Moscow to Tokyo and back to DC. At that point, the Truth that the Earth is round is needed (or we have to do a lot of extra refueling). Even then, it's fine to stick with the 'truth' that the sun and other planets go around the Earth - until we get into space-flight and have to factor in the Truth that Earth and the rest of the solar system orbits the sun.
I think Oniya is on to something.
Absolute "truth" is a rather nebulous notion, freighted with all sorts of semantic baggage. But, objective utility, that's.... well, that's something useful. To the extent a map of the darkness permits us to avoid painful encounters with hard objects, it is sufficiently "true" from this perspective, notwithstanding that it may be replaced one day with a more effective map.
Take Newton's conception of gravity as an attractive force, exerted instantaneously through ether-filled space, by bodies with mass upon other bodies with mass. Einstein's more comprehensive theory of general relativity showed the model not to be entirely accurate. However, it remains sufficiently "true" -- i.e., useful -- for a lot of stuff, like calculating the tides and the velocities of falling bodies. Getting a grip on black holes is another matter, however.
From a utilitarian view, the theories of both Newton and Einstein are "true" to varying degrees, with Einstein's being truer (i.e., more useful) for permitting prediction of a greater range of phenomena, and doing so without Newton's unexplained construct of the "ether." In this sense, the Ptolemaic geocentric model of the heavens is also "true" for backyard astronomy purposes, as it permits fairly accurate predictions of the observed motions of many celestial objects.
In a world where there is truth, then these concepts have a right and wrong. Because you cannot establish a criteria to rate or measure them does not exclude them from having a right and wrong answer. These are more than simply opinions but questions that require answers. Such questions as when does life begin, when is murder acceptable and who has freewill if that will exists have shaped the world. None of these are objective question but all have a true answer if one believes in an ultimate truth.
Saying that none of these are "objective" questions assumes your conclusion. Saying they have "a true answer if one believes in an ultimate truth" only begs the question with which this thread started.
I am puzzled by any notion of "truth" divorced from efficacy. "Subjective truth" strikes me simply as shorthand for saying we do not yet have entirely satisfactory explanations for why some people do the things they do. But, to confess incomplete comprehension is hardly a concession that the phenomena we call "mental" or "emotional" or "moral" belong to some separate category of knowledge, incapable of objective modeling and verifiable prediction. Advances in neuroscience have already opened part way the curtain which has concealed the mechanism of human impulse, and I am sure that fuller objective explanations of such mysteries as love, empathy, delusion, and religiosity will continue to emerge.