So far I have only used the Numbers portion of this package due to time constraints. But not having the feature of locking cells is in the opinion of some reviewers and many users a real drawback. I would whole heartedly agree, further I sincerely hope that Apple will re-instate this feature in a future release.
It is note worthy, users like myself have been able to almost entirely replicate this feature by using some creative techniques found right in Numbers along with its ability to produce shapes. Although it does not cure it entirely, what remains uncured in most cases is likely not that important.

More information on this may be found at the Apple forums.
Or Google
"Apple's Numbers no locked cells "

Also Might I suggest contacting Apple let them know of your feelings. The more they hear the more apt they are do act.
Thank you for your attention