It's probably worth noting that the OVAs are likely more related to the original webcomic rather than this serialization. The art style difference is pretty large just from that, the overall animation quality would depend on the budget too of course. Differences in the story and pacing could be from that stuff too, to some degree. I'm not familiar enough with the original or the OVA episodes to say for sure either way. But as for why this hasn't been further adapted into a full on TV anime or such, same reasons as usual I'd assume. The studios are already doing a ton of other things for years to come with how many things are planned, and investors don't necessarily agree with us on what could be a success worth their money.