The two cards are different and serve different purposes.
Bodhi does give an extra blocker to stop another source of damage, but he’s slower for a deck that runs through focus than Luna who allows that ally slot to be open for another ally to be placed immediately and gives the 15f right then instead of waiting another turn for the Sun Lotus to die. It’s the difference between Mental Acquity and Concentrate.
There is basically no difference between Amp and Frost, and both serve the same purpose and fill that purpose equally well. Could 1 HP make a difference? Maybe, but in my experience Amp would have died just as fast as Frost based on the amount of damage Frost takes in the games I play.