If there were only single-class characters, I think there would never be a problem with "front-loadedness".
Instead, the multiclass rules, although a gorgeous improvement compared with AD&D, still have a serious problem. As they are written, it seems that the original idea was to allow PCs with 2, 3 or more classes always kept at the same level (except obviously 1 level of difference while advancing), just as in the old days, with a new option: the favored class can be "any level".
This was supposed give a new possibility: to have a PC which is mainly of a class and marginally of another, as long as one of the 2 is familiar to his race/culture.
Unfortunately, this is very frequently abused to have a PC which is basically single-class plus the 1st level of a couple of others exactly just to get the 1st level benefits, which is always the most important level.
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Now, why the Ranger is the worst case? There is a common circumstance when you have little reasons to take 1 level of it.
If you are a Figther, a level of Ranger gives you 2 more feats and 2 more skill points (or 8 if it's taken first) and a Favored Enemy bonus. Drawbacks are that you don't choose the feats and delay Weapon Spec to 1 level later. *
That works as well with the Barbarian and the Paladin, but the alignment restriction at least makes it more difficult for the latter.
Spellcasters are less likely to delay 1 level worth of spells, but still some may take a level of Figther or Paladin for the full proficiencies.
I think that it should be fine to front-load every class, after all the characters start at an adult age usually, and are supposed to have "gained" their first level in all previous time, while the level up very fast. It's when they multiclass that it starts making less sense and problems arise. That goes for every class, but in my experience, I have just seen too many combat-oriented character taking the 1st Ranger level (and maybe didn't even exploit the feats at all).
* I know it sounds a stupid artificial example, but if you play a Human/Dwarf Fighter early or late you have to face the question: do I want a new feat or Track+Ambidex+2WF+2skillPoints+FavEnBonus? You must be brave to be able to resist