But the combat is so broken.

I largely agree with the OP and often get bored in sandbox style games because they often lack a sense of purpose or direction.  Lots of people complain about games that are "linear" but if the game has quality writers then it can be worth experiencing the game in the order and with the pacing they intended...

They're alright.  InFamous and GTA4 are the last 2 sandbox games I actually enjoyed this gen.

But you can fly!

Excluding RPG games:

Bully or Yakuza 3...that is all I have to say.

Most genres these days become a product of a success formula (RPGs, FPS, Sandbox), until the genre dies down a bit and developers become innovative again.

I think the only open world games I have ever enjoyed were jak 2 and 3.  But there was so much variety that It didn't feel open and boring like most open world games feel to me.  

Most sandbox games I don't even bother with the side missions. I'm pretty much done with the game after finishing the story missions.

Despite the worlds getting bigger and more open it seems that the missions get more lineair and restricted. Do it the way the game wants you to or start over. In GTA3 I got around the horrible shooting mechanics by forcing a car in tight places and backing over the perps. Nowadays every mission has to involve a long shooting gallery or tons of spawning thugs.

And if I do the story missions after eachother why do they always react as if they haven't seen me in ages. Hey lady I just finished picking up your missing cow, killing 50 thugs in the process, 5 seconds ago.

The best sandbox game I played is still frontier elite 3. I didn't even notice there was a story line until a few weeks into the game. Too busy exploring and trading to afford the biggest space ship then try to land it manually on a planet.

I'm sad you feel that way. The idea of sandbox and open world games is incredible and they'll usually the absolute best games (Oblivion, Assassin's Creed, Morrowind, Mount & Blade, STALKER, Red Dead Redemption, Dark Age of Camelot, Fallout 3).

As much as I love parts of Red Dead I really have to agree I mean a lot of it was insanely boring I mean

5 minute cut scene; ride for 10 minutes, do 2 minutes of shooting *repeat over and over again*

The worst though was the things like herding which was just awful gameplay, the fact that the end of the game made me do that again really lowered the game in my eyes a lot, especially since it was also the point where the narrative took a running jump of a cliff

GTA IV also had problems too, the thing I like about sandbox games is being able to do the story and then work on side stuff afterwards but GTA IV refused to stop telling me to go play pool annoyed the hell out of me. Plus the fact that they removed half the stuff I loved about San Andreas

There's some great sandbox games but a lot of them just fall into the trap of just becoming insanely boring