That's not considered a good enough investment?
What counts as a good enough investment for an investor is the percentage of how much money you made compared to how much money you predicted you'd make.
That's the metric that counts, because the amount of money per share that an investor puts in your company is always based on a predicted outcome, since that's the only information the investor has when he puts the money prior to the game(s) launching.
So if you tell me your company will make 10 million in 2020 then 5% of your company's shares are worth X. If you had told me your company will make 2 million then 5% of your company's shares are worth Y (which is substantially less than X).
Within that context, if you told me you'd make 10 million in 2020 and I purchased 5% of your company for X, but then your company only made 2 million, I'll consider your company wasn't a good investment because I should've paid Y instead of X.
And in the end, it doesn't really matter if you made a profit of 10% or 1000% within the 2 million your company made. What matters is your prediction failed by 80% and I overpaid for your shares as a consequence.
To summarize, the problem here is how much revenue Blizzard promised to make on Diablo 3 game sales + microtransactions because that determined Activision|Blizzard's share price.
The fact is that a game that successfully distributes millions of copies and then gets an engagement of microtransactions from wales is bound to make
a lot more money than any game without extra monetization. A full fledged game that sells 20 million copies can have a ROI of 2000%, but that still pales in comparison of the ROI provided by a popular $2 horse armor made by an artist during an afternoon.
Once Blizzard predicted a constant flow of revenue based on microtransactions for Diablo 3 through the auction house, there's no way they could match that revenue on sales alone.
That's why it's extremely hard for developers to cancel the implementation of microtransactions. It's not because it's technically difficult to shut the thing down, it's because when they do so heads will roll since the expected profits are going to be a fraction of what was promised to investors.
If anything, the gaming industry is doomed because of unicorns like FIFA Ultimate Team and PUBG that generate such an absurd amount of money that completely spoils the investors' expectations on how much revenue a videogame can or should make.