Asking for your wage

Some mission organisations get their missionaries to ask for money directly and others do not. Some of the reasons I've heard for not asking are because: God has promised to provide; he has told us not to worry about this; asking for money is never included in the duties of a pastor and his focus should be elsewhere; and Paul only ever asks for money for other people. So rather than being asked, congregations should be taught from the Bible that they should give.

However, it seems to me that if a worker has a right to wages and if it is good for people to give, then there can be nothing wrong with asking. Not asking looks a bit like adding extra laws to me - if all that has been prohibited is not worrying and if all that has been commanded is teaching and shepherding the flock, then why add an extra rule (do not ask for money) - why not just ask for money while being obedient to these things?

I think the strongest argument for not asking is God's assurance of provision (Mt 6:25-34) - and yet if "seek first his kingdom and his righteousness, and all these things will be given to you as well" does not rule out working for a living (as in commanded elsewhere in Scripture), then there is no particular reason to think that it also rules out asking for your wage.