Sales units for Apple went up a lot, but the total tablet sales went up even more.
There will always be a healthy market for low-priced tablets. Many low-end tablet buyers would never have spent the money for an iPad, so they are not lost sales for Apple. However, over time, some of these low-end tablets will be stepping stones to future iPad sales.
The Galaxy Tab 2 is a compelling story: cheap price with cheap memory expansion. It's no surprise that this baby sells. A lot of these owners won't do much with their tablets beyond email, web, and a few games. These customers will be happy. Some are expecting to do more, and expect that their tablet is a cheaper equivalent to the iPad. They are finding out that it isn't (read the 1-3 star reviews on Amazon). Eventually some of these customers will spring for an iPad.
Eventually Samsung will improve the Galaxy tablets so that they are closer to a current iPad experience, but they are not there now. By then I expect iPad models to be even better, maintaining the gap in features and value.
In the end, profits trump market share. If Apple has "only" 43% market share but 70%+ of the profits, how bad can that be?