I'm quite certain someone suggested this some time ago, but I think it was ross who made a good point about it not being fair for players like himself who actually do have the skill to solo upper tier levels as a level one (or just low level in general) and placing a restriction would be unfair.
Also limiting levels to 1 per game would just be preventing the inevitable if you're providing OP amounts of exp.
The only logical solution would be to scale the amount of exp you could receive when you are a certain level.
Example:
Level 1: anything past level 15 would give you 100 exp.
level 100: anything past level 172 would only give you 3k exp
level 221: all levels give their normal exp rate and there is no penalty for being too high of a level
bonus: if you wear the appropriate armor for your level, you get an exp boost similar to tier 3 or maybe if you play the elite level appropriate (a lvl 1 playing level 8 ) you would receive 2x exp on top of your membership if you had one.
alas it's a pretty complicated idea, however would make a perfect solution in my eyes as to not restrict veterans from attempting to craft their skill on a low level because lets face it, this game is mainly vets.