Upgrading electrocute

Electrocute has 70power, thunderstorm has 90power and super thunderstorm has 120 power. Why is that upgrading electrocute add only 3 power while both thunderstorm and sts add 5 power. Even it gives an increase chance of critical hit, it makes less of being an advanced skill.

The critical hit rate also increases when you upgrade it. and at (I believe) critical hit is 200% thats a good amount of damage.

yes, imagine a bolster neon with this, a guarantee critical hit, like underdog power, you do twice the less damage but critical hit denies it unless u got evade but other talents are better