Having played Skyrim since release ... I can almost totally agree with the OP. Seriously just take a look at the bug fixes in the UNOFFICIAL PATCHES. Seriously it's like the devs never even tried.
O.o the bug fixes in most of the unofficial patches are mod work fixing. making them compatible with in game stuff. Think people are missing what modding truly is. it's just editing what is already in the games code. Most mods are not brand new core coding.
They take code from the source and just edit it, making it do something else...that coding doesn't just come out of thin air O.o The company making the game makes the core. What it can handle and do mod wise is based off that.
No, the unofficial patches for skyrim only fix bugs that Bethesda didn't, they're not about compatibility with other mods at all.
It wouldn't be totally unfair to say that Bethesda is a company that relies on modders. Their games are generally clunky in various ways but modders generally pick up the slack.
NWN1 also is a game that relied on modders as a crutch, the game's OC was just a tech demo for the toolset and so boring I didn't even manage to finish it. The only reason it's remembered so fondly is because of the great things modders did.