I think your real question is " are teir 1 and 2 classes overrated at lower level games". Clearly we all know casters gain more in the second half then the first. Also, I agree, most games do not run the full course, low level games are more common. However all of your examples were based on arcane, divine classes are pretty bad ass at level 1, and just climb from there. Are arcance classes squishy at low levels, yes, however as it has been pointed out the teir system mostly measures ability to problem solve, not deal damage. If measured with that in mind, I still feel its accurate.