I like Subaru as an MC/Person/Character, I think lots of people have failed into the misconception that unlikeable MC == Bad character.
Honestly Re:Zero is making me reconsider whatever scores I gave (or may give) to other shows and lower them slightly. I never thought about it but the fact that we're talking about flaws as if they were such precious/rare traits when they should be the norm is worrying, even your averagest MC is kind of a Gary Stu under this standard (or at least compared to what a real person would be).
Maybe that is a bit unfair, considering most anime are made for escapism's sake, it would be out of place to have realist characters. Perhaps the problem lays within people's expectations, when is it okay to have a character with flaws? or a character that says/does asshole things? should self-insert MCs be the norm even if the self-insert aspect is meaningless?
I think Subaru has touched some people's nerve, he is a NEET with an above-average strength and a power that lets him fix things when he fucks up, we don't know much about his past so it is really easy to put yourself in his shoes. As you have pointed out, if you think about it, it is really easy to find what has happened so far unsurprising. His obsession, his lack of observation and his hot-headness, all of them are traits of people like Subaru, NEETs that failed to adapt to society and are thrown in another world unlike his own, saved by a hot chick and pissed by this world's outdated society.
And thus this first disconnection with the MC happens, you see all of these people screaming at him "Stop fucking up!" "Keep your mouth shut!" actively hating on him without realizing that he was like this all along, and dying over and over again just made all of these things easier to see. At the moment (Eps 1-14), I would go as far as to say that Subaru is not a character that is developing, it is more like a character that is slowly showing his true self. Whether he develops or not is up to him, and it could be for the better or worse.
Finally, I think hating on Subaru is seeing things from a very narrow minded pov, something the show has shown is not a good idea. Hating on him because of what he does/the way he is, is completely missing the point of his character, and if you think about it for a moment it only becomes even more obvious.
He ended up like this because he is a NEET, likely because of something shitty that happened in his past (people don't end up being NEETs without friends for no reason) this made him develop this personality of his where he seems cheerful and okay most of the time but when he breaks there is only anger and despair. He IS weak, and even if he tries his hardest there is nothing to back it up, no sudden power-ups, no asspulls, if he fucks up he gets to try again, but at a price which is his sanity.
He has no control over what is going on and nobody he can actively rely on. Sure, he can train and ask for help/advice from other people but that is something superficial, nobody can help or even know about his Return by Death and the only one who motivated him to strive forward left him because she got tired of him, of not being able to know what is going on. The only one Subaru can rely on is himself, and his main problem is his personality, and you can't just change that overnight, specially when you don't really have time for that when the people you love are dying left and right.
If anything, Subaru has showed how horrible people can be, cheering on him while he is as his best and kicking him on the ribs when he is on the ground. Showing not a single tinge of sympathy to someone who was thrown into a world he doesn't understand and who was killed/forgotten by the ones he loved multiple times.