I really don't think it matters how you get there, everyone does things their own way. Playing endless low wind, easy pin rounds at St. Andrews is not for everyone, same as playing every course isn't either.
When 2 tour legends meet head to head it makes zero difference how they got there, the next game is what counts.
The only downside I can see to doing it the St. Andrews way is that your average will likely go back up when you start playing other courses, whereas if you've already posted lots of scores on the tougher courses your average will be a bit more stable. If you don't mind then there really is no reason not to do it this way. As long as you don't go mad in the process.
Congratulations to the small handful who have reached the new pinacle of WGT.