It is not explicitly spelled out in the D&D 3.x core books that play changes significantly through the various levels. The lack of this explicit statement has caused, for many people, a detachment between the levels of power and the styles of play appropriate to those levels of power. This is evident from the disparity of ability between classes of different types – spell casters gain power on a quadratic curve, while those who don’t use spells grow more linearly.
Or, to use a common complaint about D&D, “fighters can’t have nice stuff”.
On top of this, because ‘mundane’ characters, those who do not use magic, learn only ‘real’ things such as combat tricks or skill use, there is the perception that much of what these characters can do should be learnable by ‘anyone’. After all, it’s just a matter of training and skill, not magic.
The name ‘Echelon’ was chosen as a conscious reflection of how D&D, especially D&D 3.x editions, actually works. Just as échelon originally meant a rung of a ladder, Echelon has explicit tiers of ability, power, or incredibility. The abilities (called ‘Talents’) gained at each level are expected to be appropriate to the tier.
Echelon was also chosen because this game no longer uses classes, as all other editions of D&D (and most d20 games) have. Character differentiation is managed through their tiers (as indicated by level) and the talents chosen. A high-tier martial character is expected to be just as awesome and incredible as a spell caster of the same tier.