That's by far one of the most common defenses for sharing. The reasoning goes along the lines of: 1) sharing is bad; 2) however sharing has some good consequences; 3) therefore, on balance, sharing is ok insofar as the good consequences outweigh the 'wrongness' of the act.
I can't agree with this argument because it falsely casts sharing as the precondition for people to find out about new bands and presumably become interested in buying CDs. Some users say that well yeah it's 2015, so filesharing is inevitable (which is true, although its inevitability has no bearing on whether it's the right thing to do). What these people also fail to point out is that precisely because it's 2015, the ease with which a band can advertize themselves and raise awareness of their music, and the extent to which this has already been done, is unprecedented. On the consumer end, it used to be the case that the only way to get to know a band is to rely on word of mouth, rent CDs from Tsutaya (or your friend), or low-quality illegal rips on the Internet. Fast-forward to 2015 where there's Youtube and Twitter and Facebook. Most bands today upload previews for their releases way before they go on sale, and some even upload the full title track and PV in 1080p. Like Owl mentioned there's even Trombe's news for all of us who don't know Japanese or are too lazy to scour Twitter. It's ridiculous to think people who still buy CDs make purchases by randomly taking a stab the dark and find new favorites by buying arbitrary releases from new indies bands they haven't heard. So the more pertinent question for me is: are these materials not sufficient for one to make informed judgments whether a CD is worth buying? If they are, then it's untrue that without filesharing the vk band will fail to gain appreciable reach to international audiences. The alleged "good consequences" credited to filesharing can now be achieved through numerous other means. If no, then said person probably won't buy the release even if someone shares a rip with him/her--in which case this entire position collapses into a poor excuse for not paying for a commodity one desires. It's surprising how some people cheerfully ignore the potential of these social media avenues for supplanting piracy as convenient (and hopefully morally more acceptable) ways to know about a band, but are always more than happy to adduce their emergence as rather dubious 'evidence' of how piracy is now ok "because it's 2015."
I also have issues with the third premise because the problem of magnitude is tricky. It draws all our attention to the miniscule gain in sales the band enjoys from the handful of people who, apparently, couldn't make up their minds whether to buy their CD after watching the band's youtube preview and had to listen to the FLAC to make their final decision--and sweeps under the rug all the losses in sales that band suffers as a consequence of this. Even if we grant that not everyone who downloads free music would have bought the music had it not been available for download, it isn't difficult at all to weigh the scales; for if it's indeed the case that piracy benefits the band in the purported way, we'll have to seriously wonder why bands bitch about illegal downloads every few days. As such it's probably less appropriate to think of the inadvertent losses incurred as some kind of 'collateral damage' that accompanies the larger good of getting international fans to buy music, than it is to conceive of the small gains in the latter group as being incidental to the harm piracy inflicts on overall band sales.
Anyway, before I'm accused of being hypocritical: obviously I'm one of those who download sometimes since I can't afford to buy every single CD I want to listen to (nor can I find all of them), and I've have been complicit in sharing a fair bit of my music. Honestly I don't think the situation now is ideal because there are a lot of things vk bands (and the industry in general) can do and should be considering to mitigate the problem. So there's still work to be done. All I'm just saying here is that I'm not convinced by the usual self-righteous rhetoric that attempts to justify unregulated filesharing, and hopefully fans can endeavor to do a little more to support their favorite bands.
Tl;dr: The pseudo-utilitarian argument of 'small harm is justified because of bigger good' fails because (1) the good can be brought about, or at least reasonably approximated, via other less damaging ways today; (2) it's highly suspect if the harm is in fact smaller than supposed good.