It can be good, but is so situational it is generally not useful for the full casters and really only usable for the EK, like you said.
First thing is that to have an effect on 8 targets, you need to be surrounded this isn't the worst thing in the world, but still generally not ideal. On top of that you probably have a higher (possibly by a lot) attack bonus compared to your spell DC, and swarm type monsters that are likely to surround you often have fairly decent dexterity, so the prospect of getting all 8 to fail is unlikely. 8d6 damage from a cantrip without the level boosts is pretty high, but it could almost as easily be 0d6 depending on saves, when perhaps a basic attack (especially if you have the cleave part of GWM) may have ended up a better bet as far as accuracy goes and potentially needing the extra damage to put a target (or two) down, assuming a weapon with 1d8 or better damage.
For comparison, in a similar ideal situation (spell area full of targets) the 1st level spell Thunderwave can do up to 18d8 damage with a push and has a minimum of 9d8. Which in fairness, does require a spell slot.
So in short, can be powerful but is so situational to not really be broken. If such a scenario happens to come up it gets to shine, which is good, everything should have its moment.
First thing is that to have an effect on 8 targets, you need to be surrounded this isn't the worst thing in the world, but still generally not ideal. On top of that you probably have a higher (possibly by a lot) attack bonus compared to your spell DC, and swarm type monsters that are likely to surround you often have fairly decent dexterity, so the prospect of getting all 8 to fail is unlikely. 8d6 damage from a cantrip without the level boosts is pretty high, but it could almost as easily be 0d6 depending on saves, when perhaps a basic attack (especially if you have the cleave part of GWM) may have ended up a better bet as far as accuracy goes and potentially needing the extra damage to put a target (or two) down, assuming a weapon with 1d8 or better damage.
For comparison, in a similar ideal situation (spell area full of targets) the 1st level spell Thunderwave can do up to 18d8 damage with a push and has a minimum of 9d8. Which in fairness, does require a spell slot.
So in short, can be powerful but is so situational to not really be broken. If such a scenario happens to come up it gets to shine, which is good, everything should have its moment.