Rift Wizard Design

 Seems the design goal is for high-level spells to be weaker than cantrips. That way everyone has "more ways to win." Very American: a design where, if the the high-level spells feel powerful, it is due to a flashy illusion. Anyone numerate will note they're mediocre at best...but of course playing vidja while numerate basically makes you an idiot. "You know thing? No fun allowed."

 The problem is primarily opportunity cost. A level 8 spell costs 8, and a cantrip + high-level skill also costs 8. The cantrip + skill is going to be marginally better than any high-level spell, unless the high-level spell is absolutely busted. Even if it's exactly even, you can power-curve the lower-level spell with cheaper upgrades rather than having to bank currency for 3-4 rifts to afford 7/8 all in one go. 

 If higher-level spells weren't basically weaker than cantrips, they would be gamebreakingly good. If a 7-cost skill gave you less of a power boost than an 8-cost spell, as long as the one-cost spell can reliably win the game (provided you don't play like a bonehead), then the 8-cost spell is basically going to be an auto-win button.

 But it's okay. Rift Wizard isn't supposed to be hard. It only kills you if you play while drunk out of your mind. It can, just barely, be called nontrivial - unlike e.g. a final fantasy, you can't completely ignore the enemies you're facing and win anyway. Though in fact the most common cause of death in RW is self-damage. Killing yourself due to having to see one inferential step away to notice a spell or skill can hit the caster, as opposed to getting tipped off by a giant flashing neon sign. 

 You can win both RW1 and RW2 with any cantrip. Almost the only reason to splurge out for any spell beyond the first is either to win-more, or as a self-imposed challenge. Indeed buying more spells inherently makes the game harder, because there's more ways you can cast the wrong spell. If you only have one spell, you can't pick the wrong one to cast. (Exception: a few high level spells are indeed busted and can more or less let you ignore what enemies you're facing.)