I have my own theories about why Taylor and many other models wear clothing that appears too tight.
First, l notice that most celebrities dress in tight clothing. Since these celebrities fancy themselves as trendsetters, many women (myself not included, lol) want to copy them.
Second, if we the customer get used to seeing the models in too-tight clothing, and jackets that can't be zipped up, we'll think it's supposed to be that way. So we won't return clothing to QVC that ordinarily would be considered ill-fitting. This translates into more profits for the Q.
~~Be careful when you follow the masses. Sometimes the 'm' is silent.~~