Waveslave, if you asked me it has more to do with marketing than anything else plus lies that still persist about foils sinking, etc - you'd have to ask people like DevilFish why they still try and spread such bull@$#$%? I don't understand why people bag stuff out that they have little or no experience in - especially when it simply isn't true. I don't bag out LEI - I just find flying FlySurfers a much more enjoyable experience.
When the sport first started poor relaunchability was true for people using 2-line or foils NOT designed for the water - that was five years ago! The ease and speed of water-relaunching is actually one of many areas where FlySurfer's have significantly superior performance than LEI - that's one of the main reasons I teach with them and how I came to import them!
Companies like FlySurfer are paraglider manufacturers - experts at aerodynamics but have difficulty in penetrating retail distribution networks dominated by windsurfing companies that already had distribution networks in place before the sport even started. Bit like Beta vs VHS video tape recorders - luckily the wind doesn't care what kite you're flying

Of course wherever you go now you see more LEI than foils and it breeds on itself together with the safety in numbers heard mentality and the importance of looking cool at the expense of any facts getting in the way of a good story.
See LEI vs Foil on the FAQ sticky post for all the other FACTS or see for yourself and come down to the BBQ @ Scarbs next Sunday