Reason for this is I really would like to dodge by moving around and aim to hit.

You can juke lock-ons, it's not as easy as some other stuff, but it's entirely possible.

Ok but try directing a single target heal without locking on, The tank would never know it's coming, may have to move and it would miss, the DPS are Constantly moving and you would never be able to hit them

I luv the lock on its awesome =D plus i use the circle healing more so less threat generated and i can do other stuff debuff rez etc =D