Choose your battles
The market performance of the tablets by Motorola and Samsung tablets have been weak because they have (naively and foolishly) attempted to make a full frontal assault on the ipad segment.
Specifically, they have tried to out-spec the ipad at the high-end price point.
For THAT much money, people aren't buying specs, they are buying prestige. And there isn't a snowball's chance in hell that Motoroal and Samsung will be able to out-prestige Apple at that price point.
Imho, the real growth will be seen in the mid- to low-end tablet market spaces. This segment has does not have an entrenched market leader. Also the volumes at this price point will be much higher (albeit at narrower margins). Look at how the smartphones have played out - the Android's growth has been huge - not because they have been stealing iphone sales (which doubled over the same period - while maintaining the same marketshare) - but because they tapped into a new segment.