I'm not singling out Nintendo - I don't mean to appear that way - but they are one of the worst. You can't use Skyrim as an example because it's the fifth game in a series, but in a span of almost 20 years (there were two in-house spin-offs and some mobile games, however), which isn't exactly
milking, is it? That's a fairly natural cycle. Same goes for a lot of EA's properties that aren't The Sims or a sports franchise (and even that seems to have calmed down somewhat).
What I'm saying is that no firm reuses the same few franchises with the regularity and the lack of imagination that Nintendo do. You have Mario Kart, Super Mario Bros, the Mario 64-esque platformers (Galaxy now, isn't it?) and so on. Each year brings a handful of Mario games, none of which really are all that different to the one before bar the addition of some sort of defining feature. They do put out fairly high quality releases, and they do put their time, money and effort into them, but it doesn't stop them from really being just Version n+1 of the game that came before it. A few minor changes here, maybe a feature there, bam, Nintendo have a new game to sell at full price for a number of years.
As for Twilight Princess - I perhaps wasn't clear. Yeah, they added new features and stuff, but it really was like a new version of Ocarina of Time. The map was largely the same (albeit moved around a bit, updated and so on), the whole Link-has-two-forms thing (Young & Adult in OoT, Human & Wolf in TP) - I did thoroughly enjoy it, as I have many of the 3D Zelda games I've played, but it still... felt like OoT in a way.
How is Nintendo the worst? Look at Battlefield, Call of Duty, EAs sports franchises,... Those are all (at least) yearly releases and it's pretty much the same game every time. CoD and BF are the most ridiculous, people pay full price for a couple of new MP maps and watching NPCs play the 4 hour single player campaign for them. Nintendo at least put some serious effort into their major releases and there's always something fresh about them, even if the core game stays the same.
Battlefield has two franchises - Bad Company and Battlefield itself. Bad Company has had two versions - one in 2008 and one in 2010. Battlefield 2 came out in 2005, Battlefield 3 in 2011. So no, not being milked. Call of Duty is being milked. Yearly releases with additional content, and the game is sold at a higher-than-average price. Either way, they're games made for a multiplayer audience (hence the short SP campaigns). I'm not saying the DLC isn't overpriced - it is, more so for CoD than BF - but it's really not as bad as you're suggesting.