With so many concerns for microtransactions within the forums, I thought it might be nice to clear up why it is we'll see them and why they help benefit everyone.
Why do we see microtransactions in videogames?
On average a AAA game developer spends roughly 12 million a year per 100-ish employees. Rare is a 'legendary' company, that employs 200-ish employees. I'm sure their pay is a bit higher, so we'll say 15 million per year per 100, which equates to 30 million a year.
Now add that to the fact that this was announced in 2015. 3 years at 30 million a year (for just employees) equates to 90 million dollars.
Now factor in what it might cost for utilities (electric, water). Let's say it costs 400/mo for electric and 150/mo for water (and that's probably low). That equates to 6,600/year - 19,800/3 years. So now we're up to $90,019,800. Now let's say the developer doesn't actually own the building, but leases instead. Depending on the size, we're looking at a substantial amount of money. Let's say the building lease costs $3,500/month (and that's low considering the size of Rare HQ). That's 42,000/year - 126,000/3 years.
Now we're at 90,145,800. Assuming marketing goes well, let's say you can expect 5 million pre-orders. 5 million copies at $60 a piece is 300 million. Now taking that profit and subtracting costs, we're at 209,854,200. Let's assume Microsoft takes a 15% cut of the profits. That's 31,478,130. So now you're left with a total of 178,376,070.
Finally, factor in the cost of server start-ups, server rentals, employee food and team-building, global distribution and marketing, I'd say we're looking at another 50-200 million (depending on a lot of factors) but for the sake of this post, let's say it's another 90 million. So you take that 90 million away from our previous total of 178,376,070 and we're left with a mere 88,376,070.
TL:DR Everything costs money. At the end of the day that $60 game is only $25-$30 for the developer. The goal is to net as high a profit as possible, but that will only sustain the game for 1-3 years. What happens to a game that is online-only that will need to be further developed and adjusted? How is that paid for once pre-orders are done and your influx of new players ceases? Microtransactions.
So why are microtransactions important?
Microtransactions allow the game to keep a "free-for-all" content model. With regular updates paid for by MTs, you keep everyone playing together, without locking someone out behind a paywall and the profit gains can be considerable, thus funding the game for years to come.
EDIT The views contained in this post are my own. I do not work for, or represent Rare in any way. Pricing/costs are estimated and are in no way representative to that of a Rare employee. I do not work in the industry, nor do I have extensive knowledge of it. This is my personal take on microtransactions.
TL:DR
Here's a video (for all you lazys) I found that also covers some similar aspects.
https://youtu.be/ypZZTIOR__Q
