Shink Package - Change Time?

Hello,
We are thinking of using the Japanican 2 day Kyoto tour- riding the Hikari, staying overnight and then back on the Hikari to Tokyo. The only thing is the return is between 12:00 and 14:00! Why so early?? Does it seem like it would be possible to buy the trip - and take a later Shinkansen, an unreserved seat - and would that be a problem? Japanican says you cannot take a later train.
Thanks!!

Well it looks like you answered your own question: Japanican says you cannot take a later train.

Looking at the price of these trips, it would seem that the price is based on a deal between the travel company and the rail company to fill "off peak" seats.

Well, I don't know if you want to try it, but I had a similar deal with a JTB or Sunrise tour (I have forgotten which) to Hiroshima. The return was, unlike yours, later than I wanted, but they said the reservation could not be changed. BUT - we just went and took an earlier train anyway, just that we had to chance getting a seat in the unreserved car. It seems that once you have paid the fare, you have bought passage on a train - you can travel when you want; it's just that you can't RESERVE a seat on another train.
If you have the flexibility I'd chance waiting for a later train, but with the understanding that maybe you won't get a seat.

Take the early rise version, so you arrive Kyoto at 10.00 h and you have a full first day for Kyoto sightseeing, The standard version means arrival Kyoto at 15.00 h what is very late as sights start to close at 16.00 h. Both versions are midday return on the second day. As RobBeer mentioned it is because of off -peak trains and even without reservation your special ticket is not valid on any other ( = later ) shinkansen.

This is in line with other JTB-operated domestic tours - you get better deal precisely because the train time slots are limited, and yes, off-peak hours.

According to the website, you cannot request for a later train, but I cannot tell if you could use the ticket for an unreserved seat on a later Shinkansen. You might want to ask to make sure, though - in some cases, the whole "limited express" portion of the ticket with the reservation becomes completely not valid if you do not take the specified train(because of the restriction), meaning you might have to pay extra several thousand yen to take a seat in an unreserved section on a later Hikari.