Because no operating system secures IP by default, so without something in place, wireless is devastatingly insecure.
The first round of wireless security protocols were a hack, a veneer of security designed to give the perception that 802.11 was "at least as secure" as your office Ethernet, which you'd want to secure with SSL or IPSEC anyways. That strategy failed.
The most recent round of protocols is every bit as sophisticated as IPSEC. It's no longer the design goal to provide something that's "good enough" for normal stuff, and to run VPN over for everything else.
There's a lot of moving parts in WPA2-Enterprise/EAP, and I don't love it. But it's no longer a silly strategy.
I'm not aware of any standards for Ethernet crypto before WEP, so I don't know what they would have borrowed. Something from DOCSIS maybe. Heck, the IEEE didn't even come up with MACsec until recently.
That's what the Wi-Fi Alliance does, they make new protocols. But truly, no ubiquitous wireless protocol should be trusted for any private data. Those protocols are (or should be) only meant for home users.
No offense, but this statement doesn't mean anything at all. Clearly, within the next 10 years, enterprises are going to move en masse to wireless. The cost savings are too high.
The solutions may not look like they do today --- I won't cry --- but the fundamental problem is going to need to get solved. Maybe it'll be opportunistic Teredo/6to4-style network layer security, and maybe it'll be something app layer, but something is going to get done here.