And there are many, many ways a PC that wants to duplicate a "seemingly at-will force attack" that a monster has could be made to do so as a DM?
From the Player side:
1. Is there any way to know exactly how it works? Ie, 1d10+2, that just looks like a modest-low amount of damage.
2. Is there any way to tell it is at-will? You saw the apprentice wizard use it a lot. It could be a leveled spell.
3. Is there any way to know it is related to a higher level wizard's spell?
No, no and no.
So we should talk about exactly what monster is being used, what other monsters have the PCs seen, what kind of information the DM provided, etc -- all before we decide what kind of answer the DM could make to "I want to try to learn that spell".
If they have only seen the apprentice wizard? Well, a 1d10 force damage 100' range cantrip is reasonablely easy to create that scales up to 2d10 at level 5, 3d10 at level 11 and 4d10 at level 17. Unless the PC is looking at the monster stat block, or was keeping track of the exact damage the spell did and what dice the DM rolled, this matches what the apprentice wizard was doing.
Next, what happens when the PCs run into the other wizard using a similar ability, but doing 3d10+stat and making 2 attacks? Honestly, you can create a completely different leveled spell that does that. For spells up to level 3, there is no in-game mechanism to tell what level they are and distinguish them from cantrips, barring quicken spell use, from the non-caster side of things.
So crafting a spell that does that kind of effect isn't hard. You could go with the concentration variant I posted above, make a low level version a cantrip. You can also sneak in a feat or technique or boon that lets you add your attribute bonus to spell damage rolls.
We can also go the magic item route. A wand that lets you cast arcane blast for 1d10+int damage that requires attunement by someone capable of casting a 1st level spell is a pretty mediocre magic item - common tier. A higher level version could require being powered up by spell slots, sort of like the concentration spell.
Feel free to be creative, if and only if it comes up. But in 95% of use cases, what you need is a tier-appropriate magical combatant, and these stat blocks provide it. If your players are get interested in specific details, that is part of the job of DM to invent them as needed. Adding all those details to a stat block makes the stat block worse for other uses (clutter), and any balance issues are now the responsibility of WotC and not a single at-home table game issue.