I agree with Paul - there should be far more flexibility (and given modern stock-keeping methods, there's no excuse for it). I have the opposite need - I want 1 and 2 irons available as part of a set. Most companies don't even make them now, and those that do often charge a fortune if you want them, treating them as esoteric extras. This attitude has now spread, I regret to say, to a lot of pros in golf shops, who regard you as unreasonable wanting to play with long irons.
I also think it's a great shame that the half set is now rarely sold. I think a lot of newbies would do far better playing with a half set of good clubs than a full set of tat for the same price. And for juniors, a half set is a lot easier to carry.