The reason is because if a game were purely about survival then the extent of its content could be traversed within an hour or two. I'm not endorsing this or anything, just explaining why games are like this now. When a player has a token of what they've achieved (in this case through grind and often rather shrewd use of the building system) it gives them more of a sense of an overarching goal. Honestly it's kinda like real life. What do you do when you've managed to survive? You live.

AS FOR THIS GAME, why is a dead viking warrior concerned with this weird oikonomos of building up a homestead? Uhhh I dunno, it's just the genre I guess. It does make sense to me that it would be beyond Odin's power to just give you perfect equipment from the outset though.