AO, You raise some interesting questions about the implications of Title IX, to which I know the answer, so here you go:

1. Title IX only applies to athletic programs at educational institutions, so the law does not apply to any professional sports leagues.  The NBA owns, funds and operates the WNBA as a for-profit venture, though it has yet to turn a profit.  Some of the NBA's stated reasons for operating the WNBA are based on gender-equality, but the NBA is a collection of private companies and can do with their money what they want, including losing a small percentage of it on the WNBA.  That should not obscure the fact, however, that Title IX in no way applies to the NBA, NFL, MLB or NHL because they are not educational institutions.

2. As for schools like Wabash, and other single-sex colleges and universities, they not only discriminate against the opposite sex (be it men or women) on an athletic level, they discriminate by not even letting the other sex attend the institution.  I believe this particular "discrimination," is a good thing because it allows for the existence of a select few single-sex colleges and universities as a limited but viable option in current American culture.  The reason, however, that institutions like Wabash can discriminate in both admissions AND athletic policies is because they do not take any  money whatsoever from state or federal governments, including state or federally subsidized student loans.  All money for the school's operations, including student aid, must come from private sources. State schools are obviously subject to Title IX as written. Additionally, since private schools like Duke, USC, Northwestern, etc., allow their students to accept state and federal financial aid, they are subject to Title IX. 

I hope this helps clarify your questions.

Back on the topic of The Purple Powers, while they may be frustrating for the majority of DIII programs, they are not bad for DIII. Those teams create an obstacle against which all other potential contenders must measure themselves and eventually overcome to be champions, including my beloved Wabash College, while providing a marquee rivalry that has boosted DIII's prestige in the mind's of other sports fans.  I attended Wabash's 2002 and 2011 quarterfinal games at Mt. Union and can attest that the ability to measure yourself against that team and, at least this year, entertain a hope of beating them make DIII much more interesting.

The Purple Powers knocked Wabash out of the playoffs 3 times in the past decade, but the continued excellence of those programs has given Wabash something to aspire towards. When Wabash first started making the playoffs regularly, we treated the playoffs similar to the NFL's Pro Bowl; something to enjoy after we played the Monon Bell, our Super Bowl in this analogy, against Depauw. After a decade of measuring ourselves against Mt. Union, Whitewater and our conference rival Wittenberg, Wabash's football program has advanced to the point that, while the Monon Bell Game is still extraordinarly important, the playoffs are as well. I'm not sure those advancements would have been as fully possible without the prestige and example established by the Purple Powers.

I am willing to listen to an argument that UWW has an unfair advantage due to its enrollment, but Mt. Union has a relatively small student body by DIII standards. Remember, however, that without UWW we would have had an undisputed Mt. Union dynasty these past 15 years.

As far as other advantages, I will never hold active recruiting against any program, be it in DI or DIII. A successful football tradition can be an important part of any school's prestige. Recruiting the best student-athletes is part of that process no matter from where they come. Likewise, a student athlete who values the ability to play football at the highest levels but is unable to obtain an athletic scholarship is well within his rights to choose Mt. Union or UWW based on their football prestige.

I know there is a lot of frustration about the continued dominance of Mt. Union and UWW, but that rivalry raised the level of competition and prestige for DIII over the past decade. Just imagine how exciting it will be if your school, be it North Central, Trinity, Wittenberg, Wesley or (please) Wabash, is the one to knock them off and seize a national championship. Just as long as it's not Depauw, I'll be happy for you.