THAT is the way it is. My service manager says that this transmission is unique to the Ridgeline (not shared with any other Honda product). For some reason they have designed some "slop" into the tranny. Wanna' see the best example? With your truck in PARK and on a level surface, climb up on one of the back tires, hold onto the side of the bed, and rock the truck back and forth! You'll get what feels like 6" of travel back and forth! THAT is why it Clunks when you change gears..to alleviate some of that clunk I have learned to shift slowly, pausing briefly in neutral between gears, that gives it a little play without going straight from one gear to the other.
No to sound like a dad here, but to maximize an automatic transmission's life, you should always come to a complete stop with your foot on the brake before shifting gears.
Also, you should always engage the parking brake before putting the transmission into park when parking, and when leaving, you should shift out of park before disengaging the parking brake. This will take the stress off the transmission from having to hold the vehicle in place and put it where it should be, on the parking brake system.