I respectfully disagree, I'm very fond of my self-target Bar spells, and WHM already makes good use of the AoE versions (though I would like to see a good reason to use Gain-CHR).

And your plan doesn't exactly pan out. A couple of our spell lines (En-spells, Bar spells, Gain spells, etc), already base their potency off Enhancing skill; potency break points still exist in parallel with higher spell tiers. I suppose its possible to rewrite the formulas to simply tier up the the next spell level when reaching a predetermined skill level, though there are some issues that are raised.

The first is the function of some spells, specifically En-spells. Tier 1 proc on every hit and simply do damage. Tier 2 proc only on the first hit, and do increasing damage as well as reduce the target's elemental resistance. Some players wouldn't appreciate losing the effect of the tier 1 En-spells just because they skilled up.

The second is that this would would effectively get rid of higher tiers, and higher tier scrolls by extension. There are players that care a lot whether they get new shiny toys as they level up, and I'm sure there's someone out there that cares whether higher level scrolls disappear from the game.