So let's sum it up.

No Magisterial teaching regarding the question.

We have the opinion of St. Thomas.  St. Thomas is not infallible and has known to be wrong.

Evidently the line of thinking is that due to the fact that women are subordinate or subject to their husbands, a certain amount of corporal punishment (to be defined by its proponents) is permitted in strict justice.

I submit, however, that this does not take into account the dignity of the wife in a Christian marriage.  There's a union and a partnership in God that makes this something more than a natural relationship, and as such it is absolutely inappropriate and even sinful for a husband to subject his wife to corporal punishment.  Subjection in the strict sense is the result of Original Sin, but the Sacrament elevates the relationship to something more sublime.  To me it's a sin against the Sacrament to strike one's wife.

So, for instance, it is never permitted for a son to strike his mother or any child to strike a parent.  Why?  Because we owe our parents HONOR ... as enshrined in the law of God.  Similarly, we owe our wives HONOR, not unlike that which we have for our parents.  Wives are the mothers of our children, and it's an affront to their dignity as wives for us to strike them.  It's a sin against the holiness of Christian marriage.

So, yes, I disagree with St. Thomas Aquinas.  Sorry.

II. Duties of the husband, 1. The husband should love his wife as a partner (Coloss. iii. 18, and remember that he holds in her regard the place of a father and a brother. 2. The husband should honor his wife, trusting her, treating her as a helpmate and not a slave (i Peter iii. 7). 3. The husband must provide for the decent support and protection of his wife and family, according to their state. 4. The husband must bear with the defects of his wife and charitably correct her when necessary. 5. The husband, by word and example, is bound to promote the moral and spiritual welfare of his wife and family.

http://catholicharboroffaithandmorals.com/Duties%20of%20Married%20People.html

Corporal punishment is not compatible with holding a person in honor.  So it is not permitted for a husband to lay violent hands on his wife any more than it is permitted for a child to lay violent hands on his parents.  This is rooted in the teaching of Sacred Scripture in I Peter iii.7.

You are claiming that something is a serious sin that was the accepted practice for centuries.  Somehow, during all that time, the Church neglected to teach against it.  That seems rather improbable.

I have seen an examination of conscience that asked, "Have I struck a person over whom I do not have authority?"  so the relationship obviously makes a difference.  
To strike a wife when she does not deserve it would be a sin against justice.  I suspect that the issue of justice is more important than that of anger in these cases.

Jaynek, you really need to stop egging on these sɛҳuąƖly-insecure little men who feel the need to thump their chests.  You are thereby doing a great disservice to Traditional Catholic women.  Might as well start issuing a line of "Trad" wife-beater shirts.  I'm sorry to say, but I am well acquainted with their type ... know many personally, the Trad men who treat their wives like complete garbage under the pretext of wives having to obey their husbands.  And it sickens me.  These are nothing more than sɛҳuąƖly-insecure pathetic excuses for men who act the part of tough guy only against the defenseless.  They used it to "lord it over" their wives, inflate their own egos and sense of self-importance, and do not exercise loving authority over them ... for the good of their souls.  They are not arguing from a point of reason, but from emotion.  And it's usually because they have issues with impurity.

http://catholicharboroffaithandmorals.com/Duties%20of%20Married%20People.html

Corporal punishment is not compatible with holding a person in honor.