The fact that Chazal did not repeal the Takanah and even ruled for those who asked that the Takanah was still operational, is not to say that they preferred a Bi'ah to the Hegmon over a Nisuin on a day other than Wednesday. However, the Takanah is in effect until repealed and there must be a Halachic reason to repeal the Takanah. Since, in actuality, even if the unfortunate happened, and the bride was taken to the Hegmon involuntarily she remains Mutar to her husband, Chazal did not find it neccessary to repeal a pre-existing Takanah due to a temporary unfortunate state. It is safe to assume that had the Sakanah existed prior to the Takanah, Chazal would never had made the Takanah.

The important thing to note is that the Takanos of Chazal were not mere suggestions, but rather Halachah Pesukah, and were not easily repealed. Just as there were binding rules on how to enact a Takanah there were strict rules how and when to repeal them, and as long as they were in force Chazal were bound to them. However, unlike a Din Torah, Chazal was able to overlook them on an individual basis, in certain cases such as here where it was unlikely that the people could abide.

Dov Zupnik

Just to add a short note to Rav Zupnick's excellent answer, Rashi (DH Hasem Nahagu and DH Hacha) and Tosfos (DH v'Su) discuss what Beis Din would tell her if she asked l'Chatchilah what to do. Rashi clearly rules that they would tell her to marry on a different day.

Even though Tosfos says that Beis Din will not tell her to marry a different day, he only means that as a Beis Din they would not tell her that, since they could not present such a ruling. However, the Dayan can certainly take her aside, out of court, and give her some "practical advice", that "nowadays, people are marrying on days other than Wednesday -- maybe you should follow their lead." (That is what Chazal call "Nahagu," an action that is condoned by the Rabanan and they do not try to stop it, although they cannot rule that way as a court for the reasons Rav Zupnick gave.)