I like to put it this way, iPhone vs Palm Pre. Palm Pre can multi task but it slow as crap and has a tiny screen. There's no way the Palm Pre is a better seller than the iPhone, so multi tasking isn't a top priority for a lot of people.
The Pre has a processor of the same speed as the 3GS, and faster than that of the 2G or 3G, and has been shown functioning, just about, with 50 apps running at the same time. The reason no-one brought one was because it was announced 6 months before it was available in the US, and it was a few months more before it was available in GSM flavours, and just before it went on sale Apple released the next Jesus Phone. It was marketed terribly (Seriously, have you seen those creepy ad's?) and the SDK and PDK weren't available to dev's quickly enough, so they all went to the iPhone or Android (Web OS is supposed to be the easiest of the big OS's to program for). Then there were the early issues of build quality.... Basically it was a mess, and now Palm are paying the price, which is a shame because it was such a good idea at the time...
I put it to you that the 3GS more comparable with the Droid. Processor speeds are again similar, but like the iPhone the Droid was marketed exceptionally, already had an app ecosystem and was launched on a proper carrier, ie Verizon not Sprint as per the Pre.
Now look at the sales of the Droid in the two months compared to the 2G:
Source The Droid outsold the iPhone 2G over the first 74 days.
That means one of two things, either AT&T is terrible, which it wasn't back then (Its the iPhones that broke the network with all their data usage, so back in '07 that wasn't an issue).... Or people wanted something that wasn't an iPhone, shocking thought I know
I'd love to see someone conduct a study of people who've switched between iPhones and Androids. See how many regretted changing to Android, how many regretting swapping to an iPhone, and how many moved back to their original OS after trying the other.....