Form and ROM of motion is absolutely essential!!!!!
I treat & train people from 15 - 85 years old and most of the guys who come in are early 30's & up with every conceivable injury and except for the direct contact sports related one's - they are all due to bad form.
Bad form usually dosen't cause immediate injury (unless it is really bad) , it produces slow long term injuries.
The best way to think about it is that it is like driving a car with the alignment that is off, you just keep wearing surfaces out untill they give out.
A lot of guys just train to be big and do anything to get the weight up. Give them 10-30 years and they will be regretting it.
Athletes with bad form and decreased ROM are going to decrease performance over time and risk seriuos career ending injuries.
Every day I have to stop some knucklehead doing heavy shoulder flexion / back extension (you may call them cheat curls) in the squat rack and go through a detailed explanation of what they will eventually wind up like. - I fucking hate idioits who tie up the squat racks & power rack for curls!!!!!!!!!! (especailly when I have people who need to squat & deadlift - which is every client, regardless of age!)
Sorry, got off on tangent.
So, yes form is crucial - take it from a former meathead lifter / hockey player / soccer player / baseball player.
If I would have had better form and not some instruction from an idiot coach and stretched more I would not be spending thousands on ART, Rolfing, PT & massage to get my range of motion back
S