I wouldn't say that I try to finish a game with a random skill map quickly. If you place the really good stuff in the corners, the aim would be to reach these skills in order to be able to defeat the bosses. For me, the difference between long running games and shorter games is how often I want to replay them, and why I want to replay them. In Skyrim, I spent over 100h in one run. After that long time, I want to see something different (although I might replay it one day). I have seen a large part of the content, playing it with a different character would show me the same content, although with slightly different gameplay. So yes, I know in advance that I will only play it once, and I want to play this go with the character I like most, thus I need full control over the skills. In roguelikes, the random generated content does not change much, but the fun is to see how well your character gets along. That is, the differences in the character creation/development is the interesting thing. I guess I spent more time of my life with Nethack than with Skyrim, although I could never beat it.
So yes, random skill map is for shorter games, but not because you want to finish them quickly.