If we really think the problem is 80% of the documents are not ready for IESG submission when the WG thinks it is, and if 80% of those documents have "classic" bugs, I would offer we do the (gasp) ITU-T thing and hire 3-4 full-time, PAID (i.e., IETF/IAD/ISOC staff) experts to review submissions before they get to the IESG.
I am not clear why you suggest this is an ITU-T thing.The ITU-T do, indeed, have an editorial staff. They operate on documents after they have received the equivalent of IETF last call (that is consent at a plenary meeting). This is pretty much the equivalent of the RFC Editor.
It seems that you are proposing an earlier pass by a professional staff. Sounds expensive, but maybe the authors/WGs would be willing to see this happen to speed up their documents.
I wonder whether there is a volunteer staff who could do this. After all, we have several area directorates (including GenArt) who review documents, and we have several enthusiasts who like to look at RFCs and raise errata.
Adrian