I suspect that people think Very Good offense limits will be sufficient because they've already made up their minds on their builds. In particular, I suspect that people have made up their minds on the kinds of Speed levels that they want. I'm beginning to suspect that CAP 4 may want to be decently fast and decently powerful. Throw the desire to have decent mixed offenses in there and we might quickly run into a problem. In fact, if anything, relaxing the BSR and/or offensive limits will (I think) make good mixed offensive builds more likely, not less.
I'm saying all this because I'm really wondering now about what we're going to do with the Speed stat in particular. Offhand, I find a build similar to Latias, with physical bulk instead of special bulk and more Attack, rather appealing. Of course, Latias has "Fantastic" grade Special Sweepiness and high "Excellent" grade BSR, and I'm not necessarily suggesting we should go as far as Latias on most of the stats. I suppose it's worth fishing for ideas about this thought, though.