My point isn't about trying to avoid taxes or to prevent coinbase from reporting on their users,
It's about helping the users who could now be facing audits where the IRS rules don't begin to fit how people actually use cryptocurrencies, users unable to comply with IRS or to afford to hire help, an IRS eager to make examples of non-compliant bitcoiners.
We are still in a time of wild experimentation and speculation. For example many were:
-trying to live/travel by spending BTC in many small sums
-building bitcoin inventions like ATMs, arb bots, apps
-speculating on various alt coins that disappeared
-lost large sums to mtgox, mintpal, thefts, etc.
So my guess is many others lost money, not just bought and held BTC at coinbase ... and are unable to document much.
There are few tax lawyers claiming to specialize in this and they charge crazy fees since they expect bitcoiners to be rich.
If each coinbase user has to seek out such expertise, many could be broken while the lawyers benefit.
IMO it would be much better to have some kind of common expertise available for the affected class - a 'coinbase victims fund'.
And it's not just for the benefit of the first batch of IRS targets. The IRS will use their chainalysis software to trace out the counterparty graph and expand their expedition beyond the coinbase records, we can be certain of that. This effort will ramp up, expand, and will impact a much larger crypto-user community. How the first targets fare will set the precedent.