Our group does not avoid attack roll spells. But I would see that someone who is a D&D numbers geek would realize that the odds of hitting are typically slightly worse than the odds of failing a save at low levels for foes that spell slots are worth using on.
For example, most saves are in the +0 to +2 range, even for bosses and lieutenants. So, a DC 14 low level save will often be missed 55% to 65% of the time. That same +4 to hit against AC 12 to 16 will hit 45% to 65% of the time (less if the foe is real tough with an AC of 18). Except for a few brutes with low AC, the save spells tend to work better than the to hit spells.
Playing the odds means using save spells instead of to hit spells, but not by a lot.
The opposite is true if the caster uses his damage spells mostly against mooks. In that case, real low AC means that the odds of hitting are higher than the odds of failing a save.