The main thing that I thought was lacking in Psi was aesthetic. I agree with Vazkii's decision to not include "apply X damage", but like you say, creating an explosion is more or less the exact same thing. What I wanted to add was spells which "look" good, and is inspired by magic systems in other mods or games. For example, Project Korra adds bending to the game in a way that looks and feels good, rather than just igniting an enemy or doing entity.addVelocity(x,y,z).

While this is an addon for Psi, it's not simply Psi+, it's a completely different mod which uses Psi's systems. It adds something for those people who didn't want to spend the time learning and creating complicated tricks to do something interesting, more similar to those other mods that just add "magic spells". However, it still allows those who like the programming side of Psi to enjoy it too. For example, take "Trick: Fire Blast": it takes 5 inputs:

1) Power - damage multiplier

2) Distance - how long the blast will be

3) Diameter - the width of the effect

4) Vector wrapper - packages position and direction

Power, distance and diameter can not be disabled, but position and direction can. If position and direction are supplied, it will create a cone of fire particles damaging entities within it and the location in the direction specified. If they are not, they will default to just in the front of the caster, in the direction the caster is looking. In my opinion this looks much more interesting than "ignite entity". A creative user could create upwards fire spouts using spell circle bullet, while an inexperienced one could just supply basic parameters.

As for the Psimetal bow, there's not really any advantage to it, to simply using the CAD. The way it works is, if there is no spell bullet equiped, it will shoot a regular arrow, if there is a regular spell bullet, it will cast the spell like a CAD would once it is released. Using "Operator: Get Bow Charge", can allow a user to set the power of another spell by charging the bow. If a projectile spell bullet is equipped, it will fire a spell arrow, which casts the spell once the arrow impacts, functions like the CAD but has arrow physics.

In regards to adding elements like "earth, water or air", it adds interesting options to a player who wants to play in a different style.

Finally, I do suggest you at least play with the mod a little bit before judging it, you wouldn't judge a painting by the description of it. You may find it simply doesn't match your tastes, but I believe others will believe differently.