It seems to me most/all of the objections to this discount the significance of answering the question well and instead focus on minor technical hassles and how it will impact people potentially providing an answer (e.g. "Why would you want our crap?"). Perhaps this misses the forest for the red tape, so to speak.
I'm kind of baffled as to why these paths don't exist already. WRT to good questions:
WRT to bad questions, good questions should not be restricted from migration because bad questions exist. Further, if somebody has to deal with crap, I don't see what difference it makes whether it is dealt with here, there, or wherever. The larger community of which we are all a part is Stack Exchange.
Another objection which seems to assume there is nothing to be done about the lowest common denominator and that we must all simply throw our hands up on a race toward the bottom is
Migrations are abandoned more times than not (unless the user is already a user in both places)
If we were selling product for money, this kind of statistical analysis might be useful, since getting paid to do something the wrong way is better than not getting paid. Fortunately, such is not the case. Going back to two points I've made already:
That new linux users would benefit from understanding the difference between distro specific question and general linux questions.
That the community in the large is actually SE, not AU or U&L.
Migration is a positive thing even if it often fails to bring the user, because not migrating is certain to fail to bring the user (i.e., it is a gesture of pure defeat). People should be encouraged, not discouraged, from learning about the various boards. Given time, this would likely increase the amount of cross-over; saying that there isn't enough now so we can't do this is like saying there's no point in building a bridge here because there's not enough traffic crossing the river.
That's ass-backward. The reason there's not enough traffic crossing the river is because there is no bridge.