Okay, let's remember that norse mythology is non-canonical so the depiction of a god may well have varied both regionally and over time.

It seems contradictory to worship a god that has so many negative qualities to what was thought to be good.

Well there is a theory that Odin was originally more feared than worshipped but that this gradually changed over time. In older references he is often called the blood god, the lord of geists or even simply the murderer. This shift may have come around the time of the germanic migration when worship of Tyr didn't seem to be working out and people sought something else to bring them victory at which point Odin rose to prominence as a god of war. This does roughly coincide with the rise of berserker culture and the Ulfhednar, warriors asociated with virtues of Odin (death, wisdom, fury).

The way he stole the Mead of Poetry seemed to be very Loki-like, and him being a blood brother with Loki are both huge mystery to me.

He was in some aspects not unlike Loki and there are numerous accounts of Odin suffering bouts of bad conscience over this fact. Particularly after the death of Baldr and Lokis punishment when Odin stuggles with the fact that much of his power (Sleipnr, Gungner & Draupner) was gained through Loki.

In this context it is worth remembering that Odin was very different from the other gods. He has was a thinker, a diviner and relied much more on deception and trickery to win than Thor or Tyr ever did, yet his warriors were by contrast extremely violent and straightforward in their ways.

Also, he seems to have an intense thirst for knowledge and wisdom, yet did not act much on it.

I mean he did essentially crucify himself on Yggdrasil just to find out what dying was like (keep in mind that norse gods were not generally considered immortal) and rip his own eye out for the ability to see glimpses of the future. He also had his ravens who informed him of almost anything that happened in the world.

He seems distant from the narrative, except during the creation of the world. Thor is much more active and I think he would have been more likely to be worshiped than Odin.

And this may well be true. A prevailing theory is that to the average warrior, Thor or Tyr were the prefered gods whereas leaders and older warriors were more prone to turn to Odin for guidance. In this context it might also be worth remembering that the norse did not really pray in the ritualistic sense we think of in a christian context. Aside from sacrifices made to ensure safe journeys or good harvests one generally did not ask gods to solve problems but for the strength, wisdom, endurance or other means needed to solve a problem yourself. In that sense Odin may well have been a good deity to turn to for wisdom, foresight, patience, cunning etc.

The Lost Beliefs of Northern Europe - H.E. Davidsson
Berättelser ur Svenska Historien - Starbäck & Bäckström