because most users have no idea what an lnurl is. expecting users to go update that after connecting a wallet is insane. most users will not have a separate send and receive, this is already way too complicated. for users who want this setup they can adjust manually after NWC connection.
Discussion
I agree it adds an extra complication. Would there be a way to use the NWC as the default for both sending and receiving via the lud16, but allow users to override that by using an LN url in their profile if they want to have a split configuration? At least that way it would be straightforward flow and wouldn't create these conflicts based on how a client decides to handle it?