The WNBA is the best women's basketball in the world. Nika is getting the opportunity to compete (a little during games, but a lot during practice) against that high-level competition and learn how they prepare and what is expected of them as pro athletes. All of that is invaluable.
Most professional women's basketball players make most of their money, endorsements aside, from playing in Europe. Being a WNBA player certainly enhances her résumé so that she can have a more rewarding Europe pro contract. That is another huge plus from her tenure with Seattle. I also have to think the way the Storm was promoting her, particularly early on, positioned her to get decent endorsement deals.
I will say that I did not think it was a given that Nika would be drafted by a WNBA team. Her measurables and statistics are deceiving in that regard. She's not the tallest or fastest player out there and she didn't rack up a ton of points during her college career. On the other hand, she did rack up a record number of assists, which one would think would be attractive to programs that already have scorers at virtually every position. Also, we saw that she scored when needed and when left open, so having her on the court isn't a vulnerability where the opposing team can effectively play five on four on defense.
Nika's greatest asset, in my view, is her indomitable will. Man, that kid likes to compete and takes every possession personally. That's a huge benefit, but it's one that doesn't show up on paper. At least not readily.
So, to sum up what ended up being too long a post, Nika got drafted by a great team, which gives her a learning opportunity and improves her résumé and name recognition. All of those are good things.