Overleveling vs Underleveling

[Koh]

I may not really be into arr-pee-gees but I see the idea behind underlevelling

You don't learn the nifty neat newer skills that make later fights easier and instead have to make do with your earlier skills, sort of like playing your starter from Pokemon without evolving or learning more powerful abilities, in turn trading off power for more Power Points to attack with

Kingdom Hearts you learn pretty much all the better abilities by levelling up so not learning the best ones by underlevelling can make the game a challenge - I'm pretty sure II Final Mix+ comes with an ability that actually forces you to underlevel throughout the whole game or something silly like that

Paper Mario, you can't wear as many badges and have to get really good with guards and in the sequel, Superguards, which aren't always easy to pull off, so that could legit be a challenge

Those being the only RPGs I've experience besides a couple Final Fantasies I can't remember, though I'm sure the same prospects carry over relatively well, so I can see the idea behind underlevelling and how it can provide a legitimate "challenge" (I don't really think Pokemon and Final Fantasy would require so much thinking as luck, Kingdom Hearts and Paper Mario I could see as needing very good skill to get through underlevelled as their gameplay is focused more on player input than computer numbers), though I myself would never actually do such things

Usually, though, the spells you're missing out on are just stronger, more costly variants of previous skills. For example, Black Mages. You'll know Fire, Thunder, and Blizzard, all costing 5 MP by the regular time of reaching a boss. But if you put in the time, you'll level up enough to have access to the more costly Fira, Thundara, and Blizzara, all costing 15 MP, which do more damage, but also cost more Mp. In fact, they're setup so they're about 3x more damage, which is also their cost value. What does this mean? Instead of having to cast the Fire spell for 3 turns, because you didn't learn Fira before the fight, you can cast Fira once with the same effect, thus really cutting back on turns in the ultimate run, if the battle is going to take a lot of back and forth. This is but one of many perks of standard or overleveling. Because really, the only things you don't have access to by those points in the game when you're underleveled are the higher tiers of spells that do the same thing of what you already have, which again prolongs the battles unnecessarily.

again, you're over-simplifying and ignoring important variables.

I'm using simple examples for the sake of showing the basic effect of underleveling as I mentioned before, which is prolonging what would otherwise be a short battle, even by normal leveling standards. Another great example of this would be Garland from Final Fantasy 1. By the time you normally reach him, the battle would be over in like 3-4 turns. But then you have the people who want a "challenge" and reach him at level 1, and thus it'd take like 12 turns or so. That's just dragging the thing out.