You can turn it off at the host depending on what your connecting too.
This is done on the remote tab of the system properties. Set the setting to "allow connections only computers running any version of remote desktop (less secure)"
The RDP client will automatically detect wether the host has NLA or not.
Personally i like it as its more secure but i see your point.
Also
To verify that a computer is running a version of Remote Desktop with Network Level Authentication, follow these steps:
1. Click Start, click All Programs, click Accessories, and then click Remote Desktop Connection.
2. Click the icon that is in the upper-left corner of the Remote Desktop Connection dialog box, and then click About.
3. Make sure that the phrase "Network Level Authentication supported" appears.