Actually, they are. It just depends on: a) who's watching it; b) how it fits into the story.
For example, William Regal and Finlay are two of the greatest wrestlers ever imo. Both of them typically wrestled slower and more methodically paced matches; yet they were so good because they told a brilliant story, and you could feel the physicality of their wrestling style every single time they went out. Another example, a more recent one, would be Orton/Henry at NOC 2011 - slow paced, but great anyway due to the excellent storytelling and character work.
On the other hand, if you get the crowd chanting 'boring' in a slower, spotless match, it's either because they're spot-craving douchebags, OR (and this is the most likely of cases) because they don't care about the characters or the story that they're being presented, and unless they are doing something legitimately cool that catches their attention, the wrestlers in question won't be accepted by them because of those reasons. Which is what I assume happened with the aforementioned Sasha/Becky (I didn't see it, I'm just going by everyone's word). That would never happen if both girls were still in NXT - hell, earlier this year, the exact same crowd (Brooklyn) was loudly chanting for Sasha, and popped crazy for Becky during the 'pre-show' for Takeover Brooklyn too. And they would mark the fuck out if Sasha/Becky wrestled a match like the one they had at TO Unstoppable, which was far from spot filled or fast paced. It just so happens that, in their current circumstance, the crowd couldn't care less because they are given nothing (or given shit) to work with and the audience is given no reasons to feel anything about their characters.