I live in a country which requires a B-1 anyway. The reason we have to apply for visas is that too many (3%) people overstay their visas or something like that. Well, I got the visa bought the tickets and got asked about my return tickets upon departing from London. It turns out that under ESTA you need return tickets, but with a visa you don't (and the reason for the visa in the first place is people were not returning). There is no common sense to this.