One day for Fuji/Hakone tour, is it possible?

Is one day enough to explore Fuji and Hakone area?

I planned to leave early in the morning to Kawaguchiko Station by highway bus and take a Kachi Kachi ropeway. Then catch buses to Gora station, use the cable car and stop by at Owakudani Station for sightseeing before moving on to Togendai and catch a ferry across Lake Aishi and get off at Moto-Hakone. And then take a bus from here to Hakone-Yumto, then train back to Shinjuku.

Will buying the Fuji Hakone Pass be worth for this trip?

Thanks.

Your plan is not impossible. However, I guess it can make you enjoy the scenery on the move, but there is no time to stay in each place.
If you're going to use the Fuji Hakone Pass, the day before the trip, you need to go to the Odakyu Sightseeing Service Center in the Shinjuku Station. It can not only buy there. There since opening at 8 am, if you buy it on the day, you will not miss the first bus.
The Pass is available transportation for your plan, such as Bus, train, Cruise, Hakone Ropeway and Hakone Cable Car, but the fee will be required for the Kachi Kachi Yama ropeway. It is the discount.

Fuji Hakone Pass
http://www.odakyu.jp/english/deels/freepass/fujihakone/
Odakyu Sightseeing Service Center, Shinjuku
http://www.odakyu.jp/english/center/