Don't need to be since I make installers for Skyrim,DA2 and Fallout mods in my spare time for people who don't want to use Nexus mod Manager creating a simple executable takes very little time tbh.
Oh, that's not how it actually works in the game industry.
You see, in a team the size of Dragon Age, in order to make sure that people are all on task and not doing redundant work, you need producers to keep track of who's working on what. You need team leads to prioritize and assign tasks. And every task, large or small, needs to be prioritized because some are more valuable than others, like fixing a cert-blocking crash bug is higher priority than fixing a small animation hitch that only occurs on a specific quest. So what actually happens is that the task gets entered into the task log, and it gets prioritized. This takes time by the programmer lead and the producer, in order to make sure that it's tasked out to the right programmer - someone who has the bandwidth to take on that task, who knows the installation system, and has the time to do it.
Maybe it's easy to do and only takes an hour to write, compile, build, and test.
Then it goes into code review, where it has to be looked over by at least two other programmers, one of whom must be a lead. It needs to be checked for correctness, stability, and adherence to coding standard. Let's say it then passes. The code is checked in. And all of the text needs to be translated and localized into all of the different shipping languages - Spanish, Italian, French, German.
Now you need to pass through the build system, to make sure that it didn't break anything. Great! The programming part is done, and QA needs to test it in each language, to make sure the localized strings are working right.
QA now has to test the installer on every platform the game goes out on. This means a clean install onto PS3, PS4, XBone, X360, and various flavors of PC. It also has to fail gracefully, i.e. what happens when the power is yanked out while it is installing. What happens when you try to install without enough HDD space.
And whenever QA needs to do a full regression (which they will be doing on a daily basis, since they are getting close to certification submission), they need to do this again to make sure it still works.
Did I mention that right now, they're a few weeks out from final submission so almost everything is on lockdown? This is getting down to the wire, where nobody is allowed to check in without personal approval from the executive producer, because they are afraid to introduce anything for fear of compromising stability.
So yeah, it's not just as easy as writing a damn installer for a skyrim mod. But it's so cute that you think it is.