I'm going to revive this by commenting and hope to hear from others because I was about to ask the same thing.
I used to change the pickups in most guitars I bought because they were all cheap pawnshop guitars (quantity over quality). One of the biggest sound changes you can make on a really cheap guitar is the pickups. Plus I liked tinkering with them.
It is my understanding that part of buying a more expensive guitar is getting really good pickups already installed as part of the guitar's tone, or the ability to request specific ones.
In the guitars I build, I use good quality pickups that I think compliment the guitar, but I wouldn't be offended if someone asked me to swap them out to their preferential set if they had one.