Hey there Atishoo,
Yep, you have indeed come to the right place for your aviation questions. Just watch this thread develop over the next few days. However, I will have to warn you that not all posters are professional pilots so you have to read between the lines now and then.
Indeed, you are right, it would have been far better if the cockpit crew had reassured the passengers that everything was fully under control, that there was nothing to worry about and that it was merely going to be a bumpy ride. Mind you, as the crew is trying to deal with the bumps, it may be a bit tricky to do a decent PA speech. However, after the bumps are over, there should be some room for a quick announcement. Especially if it was severe turbulence.
Damn, it has been 1 1/2 years since the incident and you're still nervous about it! I never imagined that passengers could be that preoccupied about turbulence. I will certainly keep that in mind from now on.
The only reason that there is an announcement for the cabin crew to take their seats is so that they will not fly up against the ceiling. Or get thrown about in any other direction. The airplane itself can withstand all this turbulence with great ease, do not worry. It is flying along at 900 kph so when it encounters a ripple of air, it will react to it fairly directly. If you hold out your arm out of your car, you will be able to feel the great force that moving air has.
So, happy holidays and I hope you'll take the plane....enjoy it! it's better and safer than the car.