The reality of it is that it's MMA and because of that they need to take somewhat of a universal scoring approach.
A jab is a technique within the art of boxing, a single leg takedown is a technique within the art of wrestling. If you secure the single leg takedown and get the opponent's shoulders pinned to the mat then you completed a takedown, that is a scoring move. The difficulty of the technique has to be rewarded, much like positions are awarded from a BJJ perspective - you are a lot more likely to win a round if you secure someone's back than you are if you secure the guard position.
Look at submissions too, I hate this idea that if you don't complete the sub that it doesn't score. You are putting your opponent in danger of the fight being over, and okay, you didn't get the stoppage, but it's still a scoring move. Taking your "pain" point into account, I could have you in a choke and it may be close to being over, you may then wriggle out and escape - you were in no "pain", but the technique is still dangerous.