I’m just more on the let’s stop potential casualties and fix the issue before it happenes again.
Who isn't?
I suspect the difference is that since the causal factors in the accident chain have not yet been identified in either the Lion Air or Ethiopian accident, some here are a bit more restrained with respect to calling for knee jerk solutions to a problem that hasn't been identified or even understood.
Accident chains are called "chains" because there is usually not a single factor that causes the accident.
Since the dawn of electrical elevator and stab trim systems in aircraft, there have been "runaway trim" incidents. As a result, since the dawn of electrical trim, there have been runaway trim and runaway stab procedures. These procedures generally prevent an incident from becoming an accident.
It is quite possible that runaway trim is a link in these accident chains. At this point, it can't be ruled out as nothing is truly known at this stage.
if that were so, one key solution would be making sure the pilots are aware of the possibility and have absorbed the procedural knowledge necessary to counter such a possibility.
It would not necessarily follow that all the aircraft should be immediately grounded. Rather, it may just call for a simple solution such as, at the extreme, a sim session or two for pilots featuring a Lion Air scenario. As I pointed out, many, many aircraft with the potential for runaway trim have been flying passengers since the very dawn of electrical trim...and still are. MCAS is, by the way, an electrical trim function.
So, I'll come down on the side of waiting until the actual problem has been identified.
It's possible Boeing forged a link in the chain if they did not properly explain MCAS in the flight manuals and did not point out the procedural knowledge necessary to counter a MCAS malfunction. Perhaps they thought a MCAS runaway would be dealt with in the same way runaway trim has always been handled. If this oversight is a factor, it is easily remedied. In fact, they have already put out an Emergency Bulletin on the subject. It just emphasizes the use of the "Runaway Stabilizer NNC" (Non Normal Checklist) in the event of a Lion Air situation.