I feel like anyone who doesn't see the story as redemptive has never been in the dark place as a NEET hikikomori.
I spent some time as one after a pretty good job I had right after high school ended. Part of the reason was that I was in the rust belt and the town's main employer just laid off 2/3rds of its workforce so every minimum wage job in town already had plenty of applicants, but I won't pretend it wasn't also somewhat my own fault for having some unrealistic expectations about the world. It was my millennial reality check. I wasn't going to get life on easy mode because being good on computers was a secret cheat skill and I was going to go work for cisco making six figures to start. I ultimately did get a job, but it was a shitty job pumping gas for half of minimum wage (no idea how that worked, I just needed a job)
Yes, that was almost 25 years ago now. Today I'm married, I have a son, I have a job scrubbing toilets at a truck stop (or something like that). It was an 8 month period back then, but I'm often reminded that my life didn't have to turn out the way it did. I meet NEETs, or I meet people who have fallen off and didn't make it to a good life in other ways, and I can see how easily I could have become that person. The way I ensured I did not wasn't by waiting until I became perfect, it was by leaving my room. It was by breaking down the walls I built between me and the outside world and showing who I was to people including the fact that I was and still am imperfect.
It isn't just about physically leaving your room, it's about a cycle of fear and self-loathing that makes you desperately want to go back even if someone coherces you outside for a few minutes. People who point out that Rudeus has negative characteristics doesn't realize that part of getting out of your room, getting out of your house, getting out of your yard, is realizing that it's ok to be imperfect, and everyone has their own imperfections, and the world isn't going to immediately and irrationally hate you for not being perfect. If you meet a woman and she realizes you like T&A it isn't this immediately disqualifying thing, and all the people on the Internet talking like there's a secret cabal waiting there for you to mess up even once and let the secret out that you're actually a man.
Then you're trapped on the Internet (I'm old so it was dial-up for me back then, and you had a limited number of hours even), and while the world outside seems so scary the Internet seems so inviting, like it doesn't care that you're weird. Altavista will just serve up the next search query without asking questions. It's why after the Internet became popular the phenomenon became so much more common.
In the end, Rudeus being imperfect is a requirement for the real redemption story -- it's about him going out into the world and being genuine and flawed and finding the courage to keep putting himself out there despite the fact that he's imperfect and he knows he's imperfect. Along the way, he also grows into a still flawed but significantly better person than he ever was in his previous life.
For the people who point out Rudeus is still flawed at this point in the story, the question needs to be: Should he go lock himself up in his mansion until he stops being a pervert then? Will that help? Should he lock himself up in the sex dungeon in his basement and stay there until he dies to ensure he doesn't accidentally offend a woman? He could, but he's had a positive effect on many people despite his flaws, including a major positive influence on Eris, Sylphie, and Roxie. Eris would have died on the demon continent if Rudeus wasn't there. Sylphie would never have learned the magic she did and would have died in the fall after the teleportation incident. If he didn't have that redemption of choosing to leave his room in this world, of choosing to make connections with people, of choosing to be open and let people in and not just put on a fake facade of what he thinks people want to see about him, none of that would have happened.
This is already kinda too long, but my favorite direct hikiomori story is Rozen Maiden, and in particular season 1. One of the top moments in anime of all time for me is in Episode 11 where Jun's sister Nori is inside Jun's inner world, and it's filled with his self-doubt and all the reasons he's a loser keep playing on TVs in a dead world. She doesn't snap him out of it by saying he's perfect, she snaps him out of it by saying everyone is struggling, everyone is failing, and admits she's struggling because she feels like a loser for not being able to help her little brother. It speaks to exactly what I'm talking about that the key isn't to be perfect, but to just get out there and try and not let your self-doubt stop you.