Can you spot the problem with the following dialog?
I expect the developers of the Steam installer are making trade-offs for the benefit of younger users - providing visuals to help match them with their language. However, using flags in software products is generally a bad idea.
These flags belong to a few (not even the majority) of the sovereign states that use English as an official language:
(Flag icons courtesy of famfamfam.com)
Which one is the most appropriate for representing the English language? Perhaps it is the flag of England ? Using the English flag would confuse those not familiar with it. Is the best flag to represent Portuguese the flag of Portugal  or Brazil ? The latter is the largest Portuguese-speaking software market.
Another problem is that the relationship between flags and languages can not only be 1-to-N; it can be N-to-N. Does the Irish flag represent the Irish or English languages? Does the Canadian flag represent the English or French languages? [Or does it mean one of the eight recognised regional languages?]
Ambiguity is not the only problem. Flags are political symbols and not all of your users are going to be keen on the associations you are making. Even within Western democracies, people kill each other over issues of national identity. That may sound alarmist - and it is unlikely that someone will hunt down, or even sue, a foreign software developer over a dialog box - but why is software even making these associations? The issue can be easily avoided, and with less work than the original approach requires:
Wherever possible, political and religious images should be avoided. Software should strive to be neutral when it comes to cultural considerations.
In the 1990's, I did some i18n analysis work on a software tool that allowed users to glue together software components, no programming required. At the time, for that company at least, the development and localisation processes were handled by distinct teams. One of the samples developed by the programming team included a map of Western Europe. When the user hovered the mouse over a country, that country's territory was filled in by its national flag. It was visually appealing, and a good demonstration of how to use the tool.
The sample had to go.
Not only was the use of flags contrary to the company's globalization policies, where national boundaries had been drawn was a potential problem. Note that the issue was not whether the developers had made the right choices. It was the fact that these choices were being made at all.