Vetoes will be decided by the Beatmap Nominators through majority vote
Something I feel is missing here, is the step from the result of a majority vote to an actual post on the map thread. One good thing in the current system is that QAT can write a post that is tailored to the situation at hand, being able to pinpoint what a map's issues are and giving specific suggestions. With a majority vote I don't really see this happening.
It should be obvious that "this is the voting result, please comply with the modder" doesn't work, it's hardly "mediation" at that point and is too impersonal.
The new Management Team won't or shouldn't write a post, it seems like they are supposed to keep themselves uninvolved for vetoes. Having them write about a discussion and decision they didn't take part in seems kinda wrong?
That leaves the BNG, you could pick representatives of the winning side to deal with it. That however, is tricky when voting is anonymous since it might lead to the representatives losing their anonymity. Non-anonymous voting solves this, but honestly, I'm kinda scared of all the potential social dynamics that come with having statistically opposing parties within the same usergroup.
Other than that I agree with Lasse; voting works when everyone wants to give an input, not when everyone "should".
I'm also wary of the dq change. Generally permissions and responsibilities are distributed among people you trust with them, you trust that they don't have malicious intent -and- they are capable of making correct use of them. So, giving BNs the option to dq, as well as veto voting and a lack of QAT to deal with things for them is a huge expansion on those responsibilities, but they're still the same people. It seems very likely that mistakes will happen. It'll be very sad if this ends up having a reductionary effect on the BNG, or even another split into separate roles.
Also agree with Nao on the scoring system. You're not really encouraging anything here anyway, you're just not discouraging it. It's also the case that, whenever numbers get involved, people will always try to give a meaning to them, even if you only use them as a guideline.
The rest seems a bit up in the air. Disbanding QAT doesn't really remove the concept of quality, people might as well go yell at BNs for not vetoing maps they dislike. "Lack of Quality control in general" would be the easiest criticism against this.
Overall this proposal doesn't seem like it addresses the root of the problem and will likely be followed with another proposal in the near-distant future. The cycle repeats.