Yeah, I don't see what the downside is either. For companies - It doesn't sound too hard to implement and seems like it would be a good source of revenue. Plus

Yeah, I don't see what the downside is either. For companies - It doesn't sound too hard to implement and seems like it would be a good source of revenue. Plus paying subscribers will be more 'loyal' in terms of moving their searches across. For users - you get more of a guarantee that the companies statements about privacy and impartiality are true, because there is less incentive for them to break that.