Re: Wait, what...?
There's definitely an element of design-in/lock-in here. However, if you've got (say) a London and NY office, you can do the trans-atlantic cross connect via AWS now. Each office puts in a (relatively cheap) Direct Connect to AWS, and AWS connects the two up for you.
For two offices that's probably not worth doing (because of metering as you say), but if you have (say) 5 offices globally, you _might_ get some benefits because AWS will sort of mesh the offices together, rather than needing say a Tokyo->NY->London type route, you just go Tokyo->AWS->London. However, if (up to now) your Tokyo office has just had VPNs to London and NY, then yeah, I can't see this really being any better for you.
In summary then... it's not a definite "yes" or "no" - it's more like "it depends", but you're probably going to have to be a "particular kind of customer" to take this on.