Its simple, because a currency needs to be spendable. If the network can't handle this many transactions then its not scalable for the world. A lot of people here believe in Bitcoin becoming a global currency, and this is why people are paying a lot of money for a Bitcoin.

I get this feeling some people against the blocksize increase think that 7 transactions a second is fine and Bitcoin will be like gold and it'll be this massive store of wealth. Well if millions of people can't move their wealth around your Bitcoins will be worthless, no matter how many thousands you have.

Bitcoins only have value because people think (incorrectly) that Bitcoin can scale up as a payment network and store of wealth, If you told CNN/BBC and every new adopter that the network is actually capped at a max of 7 transactions a second* and that a decent amount of the main developers think this is fine, and that no one will ever need a transaction volume higher than 1000 transactions a second. Then you will see that $45 drop and it will not recover. It won't recover because another system will take its place.

Remember VISA/MasterCard/PayPal only represent a fraction of money moved in the world. Everyday hundreds of millions of people are paid into their bank accounts from work, billions are moving cash to one another. If bitcoin sticks to 7 transactions a second and another crypto-currency that can handle 10,000 transactions a second comes about, one that allows users to download part of the blockchain and allows users to connect into a node instead of being a entire node themselves, that currency will win.

*I heard from a forum member a while back the max transactions per second is 7 before the 1MB is no longer sufficient.