I leased a Pilot last year and within the 1st year realized just a few little things that bothered me. First thing was that the back window in the cargo area does not open. I have a dog and would like to cracked when needed. The front bucket seats make it difficult if you drop anything between them. My blackberry fits perfectly there and is almost impossible to retrieve. The car is very peppy and tends to want to slip when you accelerate on wet surfaces. Nothing crazy, but just to get on the freeway for example. Front wheel drive no doubt the culprit. Other than these little (picky things) it was a great car do drive down the freeway during the worst storm last year. It does not get blown around the freeway which I did like..
In regards to the rain, I think your issue is realted to the 2 wheel drive Pilot- the All Wheel Drive model should not slip in this manner.
Your problem with slipping is probably more related to the tires than the vehicle. We own a 2006 Pilot, and swapped out the Goodyear Integrity (energy) tires to a more aggressive model for snow and ice. Even with a 2wd, we don't slide.