The point is, if a player is skilled enough to do it, he probably is already doing it.

The reasons why anyone would still not have done BC is one of the following:
  1. Not interested at all in that kind of stuff
  2. Don't have time
  3. Afraid of peer pressure ("what if I mess up" etc)
  4. Not skilled enough
To make BC accessible to these people:

#1: obviously there's nothing you can do if someone is simply not interested in the content. But then they don't want to do it anyway, so no reason to spend any effort catering to them.

#2: as many players have said, BC can be completed in an hour, with a good static you do it in much less than that. So what's making it take so much time for these people? The matching and the perceived time investment it requires (and the wipes plus the ensuing rage quits etc). So BC in DF, each Turn as one independent dungeon (piece-meal), plus no lockouts to vastly increase the population doing the turns so matching occurs faster.

#3+#4: make the content more tolerant of mistakes, and the simplest way to do that, is to make it easier. Something that everyone says is a walk in a park won't give people too much pressure, and they are more willing to try it.

Lockouts aren't the only thing preventing people from accessing the content. The difficulty adjustment is actually required to make it truly accessible to everyone.