Hold on for a second, you don't know and can't say you do, the long term effects of these things at this moment.
its more than likely that these things in some form will effect the game ending at least.
if you fail every class you think MC will end up as some kind of CEO of his own company or something? he likely end up in a minimart, or sell some burgers but may be that would be to hard for him to, thanks to his failure at math.
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fighting also obviously have to have some kind of effect eventually, considering that even if you play without mini games , , the major fights are still happening and there is some pattern that you have to use to win, at least as I read in the walkthrough .
here is an example :
View attachment 3547310
not skipping it entirely like the class mini games.
another thing like you lose the mansion mini games, you not get Access to Quinn lewd scenes. so to say that they will have Zero effect in the long run is can't be said.
May be it will not affect the game as heavily, sure, I mean it would not be entirely fair with those who skip the mini games, that their punished for it .
But I can definitely see it more like in an RPG, you can rush and focus only on the main quest, skipping all the side activities, but those who not skipping it and do everything , likely will have a wider experience , with aditional informations and goodies. overall a better experience.
you can skip side quest in Mass effect, not giving a shit, and end up killing Wrex, or you can go find his family armor, and " save him" , the story won't change much but, it's good that it is Wrex who leading the Krogans later, and not some random dude, we have zero connection to.
making peace between the quarians and geth. Make sure that all you team mate survie, mass effect 2 final mission etc, all these require you to invest in to these things and it has a pay off.
That is why, that as much as a chore and some times pain some of the mini games became, I don't turn them off, I don't skip them, because I want the best possible outcomes, and not a shallow endings, where I feel something is missing, do to my lazyness and not do to the developer.
I rather shit at DPC for him not delivering despite I did everything right, and not the other way around