I personally find it boring. I love soaking in onsen but after few dips the feel would had fulfill mi. I dun sleep early so i guess the best entertainment is to drink till i drop. Unlike going to Taiwan, Wulai. I stayed at their hotsping hotel for a nite. My private room with tub was facing the mountain. Dipping in the hotsping in the month of February, walking along the pedestrian street shopping for their local food & ends it with a few drinks to call it a day. Not necessary going to clubbing.
instead of going to a onsen ryokan, maybe you can consider those larger onsen hotels or resort next time? they usually have more facilities like game rooms, karaoke rooms, manga rooms, and definitely have a few bars and restaurants for you to spend your evening most enjoyably...
there are plenty of such hotels in hakone. i saw many on rakutens that comes with outdoor swimming pools, table tennis rooms and libraries.
i think it is understandable that many of the japanese visitors go to hakone to enjoy the peace and relaxation and they have maintained the environment to be such.
if you wanted some street action, maybe you can consider kinosaki onsen? that is truly a traditional onsen town and there are lots of street shops opening in the evenings in the summer for visitors to walk about in their yukatas.
