They are apparently saddled with some long-term T-Mobile HotSpot contracts, which is not a free service. The "free" internet access they are providing their own members consists of 24-hour passes good in any T-Mobile HotSpot, not just in CRC's.
Should Delta provide anyone who walks into a CRC with 24 hours free T-Mobile HotSpot access? I'd guess not.
While it might see "unfair", I think we need to wait & see if Delta doesn't get rid of T-Mobile at some point and set up really free wireless as their partners' lounges have done. It must be costing them a bundle to provide these passes.
Incidentally, not all of have have to pay any extra to use the wireless in CRC's. My primary internet access -- both at home & on the road -- is a Sony Ericsson GC-89 wireless broadband card with service provided by T-Mobile. One of the benefits is free HotSpot access.