Speak for yourself. Other things being equal, I'd much rather get cash than shares in the company I work for. If the company goes bust, then I'm out of a job and my shares are worth nothing. If I want to invest in equity, then I will buy stocks in other companies and have a more diversified portfolio.
Of course, the situation would be different if I were a co-founder or a key employee with significant influence on the company's direction.
The company is question is Mojang and being a gamer myself, I know they have a very dedicated following and very open compared to other traditional companies. Short of a massive screw up, I'd doubt they'd go 'bust' easily.
If you had shares in the company, wouldn't you care more and push even harder? That's the point I'm getting across.
In my experience, the best game developers are primarily motivated by their desire to create awesome games and their motivation level is already maxed out. Some see shares and other bonuses more as a sign of distrust than as a motivator, as if their dedication to awesomositude is being questioned.
Besides, awesomest isn't necessarily most profitable, so if you encourage your team to optimise for profit, there's a pretty big risk that the awesomeosity output rate will drop. With time you might even end up with a team churning out click-grinding Skinner boxes, which is not very awesome at all.
With company of less than a few dozens employees everyone is a key employee and what he does affects the company. Thus I think shares really boost working morale and interest in company's success. Money does too. But I think that higher stable income more than a one-time big fat bonus.
Of course, the situation would be different if I were a co-founder or a key employee with significant influence on the company's direction.