This is a new "feature". It was discussed in this thread:
http://social.msdn.microsoft.com/Forums/et-EE/reportabug/thread/11bf1d78-a5eb-4032-b470-4629eac29b0f
Quoting from that thread:
Unfortunately we battled a flood of spammers (many hundreds) over a period of months. A lot of time and effort was spent. A common characteristic was that the spam users were new and they posted images. After some activity, your new user account will be
able to insert images.
This is unfortunate for legitimate new users. Perhaps there should be a better explanation. But the alternative (unless a better method can be found) is for many people to spend many hours each day (and night) marking and deleting spam and banning the new
spam user accounts. The spam messages also made the forums unusable. Pages and pages of spam made it hard to find legitmate threads (and made the forums look very unprofessional).
Richard Mueller - MVP Directory Services