The whole "use a beginner spell that turns into an overpowered display" trope is something that I feel needs to be subverted. I feel like this is something that really shows the level of superficial wish fullfillment power fantasy of these novels. It's not necessarily bad, just overdone.
Don't get me wrong, I also enjoy this trope and love wish-fullfillment. It's just that as I've grown as a reader and given my own go at writing a novel, I can see how this is a cliche which serves only to emphasis the OPness of the MC.
I'd love it if the MC was rebuted in that he has a lot of potential due to his mana capacity and magic strength, but his lack of restraint, control, and awareness of his own power makes his OPness not a completely good thing to be in awe of and praise as genius godking talent. It'd be a source of both interest and concern that has a need for specialized instruction and close attention due to raw potential and possible dangers.
If you were killing monsters for material like leather, this level of overkill would ruin any chance at obtaining the material. Plus in a spar, it could be a deadly problem if the MC can't tone down his power.
There's more to magic than raw power. Overkill is a bad thing especially if it causes unnecessary property damage.