If Eurostar didn't have the silly security theatre or 30 minute minimum checkin (A BA flight from LCY to Amsterdam has a 20 minute checkin, BA from Heathrow is

If Eurostar didn't have the silly security theatre or 30 minute minimum checkin (A BA flight from LCY to Amsterdam has a 20 minute checkin, BA from Heathrow is 35 minutes if you're handluggage only) then you'd be right. For people traveling from Amsterdam to London. Want to go to Reading or anywhere west of London? Flight, no brainer. Want to go to Birmingham? Fly to Birmingham. St Pancras is still a tube ride from most places you want to go to even in central London. If you're aiming at Docklands it's a long way. Crossrail will help a fair bit with Heathrow too. That's not to say that eurostar isn't often the right option -- the wifi and mobile coverage isn't that bad, and most of the trip can be productive - especially if you want to get your head down in some coding, security is marginally less annoying than airports.