I think for once Apple was forced to play catch up on a new product category (and I don't count phablets as a new product category). Various companies have been working on smartwatches for a long time, and Apple seemed content to tinker until Samsung started releasing a deluge of Gear devices. None of the Gears are all that compelling in my opinion (a view likely shared by Apple), but they represent a big head start on Samsung's part regarding name and product recognition.
And then the Moto 360 was announced, and people went berserk.
Apple *had* to release a smartwatch at this point, or they would have been seen as woefully behind. Investors expected them to dominate this new category, much as they did with the first smartphones and tablets, and the longer Apple waited, the more nervous investors grew. Apple knows the Watch is not ready for prime time (hence its nebulous release date of early 2015) but they had to get it out there to reassure investors and their fans that they were in the game.
Personally, I think they made a mistake. The watch is not unattractive by any stretch, but it's so similar to the various rectangular Android watches that it doesn't stand out at all (unlike the Moto 360 and LG's new round watch). I think they've got some good ideas in the UI, but it's so busy in places that it's information overload. A watch needs to convey information simply and quickly; a glance should be all you need to get what you need. The Watch doesn't necessarily do that, based on many of the screenshots I've seen. Some are so busy you may as well just pull out your iPhone to get what you need, totally defeating the purpose of a smartwatch. It's also pricey for something that still needs an iPhone to function.
The Apple Watch has potential, but it's nowhere near the knock-out people expected. Apple has ceded crucial ground to the other manufacturers, and given them an opportunity to get it right. Early adopters will love it. The public? Probably less so.