The role of hit points has been pointed out, which is plenty familiar to me from older versions. (In 1e, a level 17+ fighter with a +1 hits plate-mail and shield automatically, barring weapon vs. armor type, dexterity, magic or other defensive bonus.) Getting another hit die plus constitution bonus every level in 3e is on average a boost.
If armor "stacks with" an innate defense bonus by level, then you get bigger numbers but armor is still important. It's actually more so in proportion as the base chance to hit is reduced: (+6 from armor) 90% = 1.5 x 60%; 60% = 2 x 30%; 35% = 7 x 5%.
A +4 dexterity bonus, of course, makes you as well protected when buck naked as Average Joe is when wearing a chain shirt or suit of scale.
To make armor irrelevant calls, I think, for a class different in that regard from the standard fighter.
If armor "stacks with" an innate defense bonus by level, then you get bigger numbers but armor is still important. It's actually more so in proportion as the base chance to hit is reduced: (+6 from armor) 90% = 1.5 x 60%; 60% = 2 x 30%; 35% = 7 x 5%.
A +4 dexterity bonus, of course, makes you as well protected when buck naked as Average Joe is when wearing a chain shirt or suit of scale.
To make armor irrelevant calls, I think, for a class different in that regard from the standard fighter.