Two other super convenient things about Shinkansen:

- You always know how much the ticket will cost, no matter if you buy it the same day.

- If you had a reserved seat but you missed your train, just take the next one and go to the free seat area. Also, if you didn't have reserved seat and the free seat area is full, wait 15 minutes and take the next train.

(And yes, you can fly Tokyo - Osaka for cheaper than a Shinkansen ride, but the convenience of the Shinkansen is really higher than any flight.)