Does the main character get any less irritating?

Just to update my thoughts as I did end up finishing the anime, I will answer my own question. That episode with the space burial was the worst and that was actually the episode that made me go and make the orignal post because like you, I found it a bit disgusting. However, it does get better as it continues in multiple respects.

As more characters are fleshed out, you will probably find more to like. Hachimaki becomes the yang to Tanabe's yin, and there's a fair amount of development for the other characters as well. Tanabe herself, while still personally unappealing, does get better. The writers clearly have more idealistic and liberal sympathies and this was probably my biggest complaint about the show, but they're gentle about their views so that it's never too bothersome, even if you disagree.

Overall, I would still recommend this series even if you find some things unappealing. That is one of its strengths I think. It paints realistic portrayals of various different people with different personalities and those portrayals don't fall prey to the one-note cliche's that most animes fall to. Real people can't be morally quantified on a single linear scale. Real people are messy. Analyze anyone and you'll probably find at least a few things you don't like about him or her. Later episodes get pretty deep into the psychology of certain characters and this is where the anime shines in my opinion.

I would rate this show in the upper echelon of anime for sure. It is indeed worth watching all the way through. I do wish they took some dark ideas further, but I won't fault it for being uplifting.