Remember, we're talking about founders here, officers of the company with a fiduciary duty to shareholders. It's one thing to hire a top employee away---he's bound by whatever IP clause is in his employment contract, but beyond that he has no duty to the company. It's another thing entirely to acquire a company's IP assets indirectly by hiring the founders via a big equity package, leaving the shareholders pennies on the dollar. I don't know that that's the case here at all, I'm just saying that it raises the issue. Obviously it matters how much they got. If it was a $500K incentive, no problem. But $50M would be a problem. Somewhere in between those numbers a line gets crossed, and it becomes an ethical (and perhaps legal) issue.
When the primary asset of the company is its team, the investors lose both their moral and practical claim on the value of those "assets".
Morally, it is wrong (and without foundation in contract law) to prevent an employee of a company from finding more gainful employment somewhere else simply to maximize the value of your investment. While it's true that every retention policy of every company is designed precisely to keep employees from finding better offers, those are carrot policies, never sticks (the sticks tend to get shot down in court).
Practically, there's no effective way to compensate investors for the value of the team, because every dollar you don't give the team decreases the likelihood of retaining team members, which is the whole point of making a talent acquisition.
All of this is a long way of making a simple point.
Gowalla lost. Its investors knew it might lose when they made their investment. Trying to claw ROI back from the value of the individual employees on the market is simply not a reasonable investor goal.
Your assertion that employees are never under a moral or contractual obligation to their employers is simply wrong. An employee in a sensitive position, under a non-compete, cannot take trade secrets from his employer and give them to another company. This is both immoral and illegal, and contrary to your statement, sometimes the 'stick' is enforced.
Even if you were right about employees, as I noted above, the situation is very different for founders. It is morally (and in extreme cases legally) wrong to accept a payoff in order to circumvent the investors to whom you have a legal and ethical duty as corporate officers.
If I invest $10M in Startup X to develop and market Cool Service, and a year later the founders accept a $50M stock package from Company Y so that it can offer Cool Service, and I'm left with nothing, then "trying to claw ROI back" is absolutely a reasonable goal. (I'm not saying this was the situation with Gowalla, only that your position that it's never justified seems extreme.)
