Initially you argued that FO4 intro backstory limits your control over your character, and thus is
contrary to the idea of freedom in RPGs. I am familiar with sentiment toward playing blank slate characters, but having a past doesn't limit your freedom to interpret and develop your character as you want, "freedom" is about the journey and the impact you make through the game, while 'blank slates' is just another tool to makes us feel more invested.
I started off by pointing out that plenty of RPG's provided you with a backstory including PST and Alpha Protocol, two title that Chris Avellon (you probably know of him) worked on and characterised as having blank slates characters, despite them offering a well defined past. More specifically to our case, indeed FO:NV story structure is different and offers us little to no backstory (basally you srr the outsider), however, I argue that all the rest follow similar structure and come with personal stories, and that the single most notable difference between their intros is the extra details provided due to the transition to 3D. So for example if FO2 was made in 3d then you'd have seen a lot more of the tribal life, including the details you complained about here (like martial status and house decoration, ho no).
Now, assuming that you aren't actually beating on the transition to 3d dead horse and open minded, I left that video to offer some insight into the question you intially posed "what were they thinking?". Also consider that generally in plot heavy games where your character is newly introduced to the world, quite often your player character has a level of disconnect from main plot, which is doubly true for players new to the series (most were), which is one of the reasons why FO:NV wasn't received as well as FO3.
Anyway, what I am have been briefly hinting at is that Bethada knows exactly what they are doing (just as Obsidian did), in fact I think that FO3 and now FO4 intro, detailing life in the vault and pre-war, are spot on for the platform\mechanics, theme and target audience.