Me too. Loved that thing. I remember when I was able to truly multitask and switch applications seamlessly. It was great. I still feel like iOS and android don't switch between apps as smoothly as I was able to do on my pre.
Build a new OS, one with support for existing apps (granted, they'd have limited ability to interact with the modern Palm OS), and you get to keep existing customers.
OH how I miss Palm. Splashshopper is still a better shopping list app than anything I use today, I used to play Monopoly on my Treo, and watch movies from the SD card when I was traveling (but boy it used battery).
WebOS really was so hard ahead of its time. A card based interface, gesture-based navigation, unified and always online email and account systems. There were many things WebOS did that we take for granted now, yet they did it no less than 5 years before Android or iOS. Really it was just the Palm Pre's hardware (I had a Palm Pre Plus) that held it back. Some aspects of it were already a bit dated, even in 2010.
I had one. I really liked it but there were a couple of major downsides I remember. If you had to reboot it, it took many minutes to come back up. It also had the build quality of a sand castle. My wife and I both went through multiple devices in the couple of years we had them. It was my first smart phone.