There was a fair amount of market research as part of 5e, mainly because the gap between forums and the reality of sales was so large that we needed a better way to get feedback.
Starting with the 5e playtest and going forward, we did regular surveys and studies to understand what people were doing with 5e and what they liked/disliked about it.
I think the methods are different - they seem to use D&D Beyond a lot more, rather than open calls for anyone to fill out a survey - but they still do that stuff. I know that they sometimes send marketing surveys to Beyond users. I received one a few months ago.
Two things stand out for me:
D&D surveys had huge response rates. People were always eager to share their opinions.
The gap between survey results and online discussion was vast. The fighter is a great example. A lot of online people consider the class incredibly weak and lame, but it was always one of the most popular and well-liked class in surveys.
The second point was a big reason why studying the market was important. Online feedback is good for tactical problems, like resolving ambiguity for specific rules. It’s terrible for strategic directions, like how complex the game should be.
