Good technique will keep your spine aligned, your neck in check and your eyes on the prize; there will be no slips at the hips, the bees will envy your knees and your feet will be neat.
Poor technique will eventually injure you. Don't be the person turning a kettlebell into a wrecking ball. I think Miley Cyrus has a song about this.
WTF bro!? → → → Looks good, brah → → → Bro, you’re a pro
Or, more usefully:
Stop right now → → → Acceptable → → → Optimal
If your technique is poor, you should avoid performing the exercise under load (with weights). Practice remedial versions of the movement until your competency is such that you are able to move with aplomb.
Poor technique is often just misunderstanding and some quick pointers will usually bring someone up to an acceptable level. If you have poor mobility and severe movement restrictions it will take slightly longer.
Acceptable technique means you can safely perform a movement under load (with weights) and you should do so whilst striving towards optimal technique. Acceptable is where most people find themselves on the technique continuum. Strive for technique greatness and the glory that comes with it.
Optimal technique is that which puts you in the strongest and most stable position you can be in for a given movement. It ensures all the forces are being applied in the right directions and at the right time. Every motion has a purpose and every little bit of effort/energy you are putting forth is going towards lifting the weight.
Optimal technique demonstrates a solidly embedded movement pattern that allows you to perform a movement safely, powerfully and consistently.
Most movements have progressions within them, it's best to achieve optimal — or close to optimal — movement at each stage of progression before moving to the next level.
For example, you should be able to bodyweight squat optimally before Goblet squatting and you should be able to Goblet squat optimally before front squatting with a barbell.
Technique is the number one priority when training. An appreciation of what you are doing, patience and good quality practice is all it takes to make improvements.
That might mean working on the movement pattern or improving your mobility so you are able to adopt the necessary positions instead of loading up the movement with lots of weight. This is essential for long term training success.
Always prioritise technique and strive for optimal so that you can get the most out of your training and you keep yourself safe in the process.