Let's look at it from a business perspective ... you have X sq footage of your store dedicated to NikeTennis in a shop where people generally buy basketball and running apparel. Why would you keep carrying product to serve the potential one or two buyers a day when the other 100 are getting running/basketball items?
So what if Nike is going online-only? We're not a big enough market, but we have our dedicated retailers like TW!
I would agree with you, except that every time I went to NikeTown, customers straight TORE through all of the stuff, I'd go back a week later and multiple items (including wristbands and headbands) were completely sold out. For Nike Chicago it's definitely not a matter of not selling enough stuff, because the golf section is right next to it, and I've never seen anyone buying anything there.
I wouldn't have a huge problem for an online only Tennis release system, except for the fact that Nike.com slacks hard on putting their stuff up. All the major tennis gear websites already have the full FW15 collection up, and Nike.com still hasn't posted a single thing, and they didn't even have half the wristbands/headbands from the past 3 seasons on there...
Considering Federer is the most marketable athlete on the planet and he and Rafa wear 10+ Nike logos every time they play a match, some of which go on for hours at a time, you'd think they would be trying to capitalize on that.
It also might help if they didn't charge stupid amounts like $18 socks and $75 for shorts and shirts and now $200 for shoes...