GC items: strange level gaps/job distribution

I use my GC Seals to buy equipment as I level up - mainly because I'd hit the cap otherwise - but I noticed something odd: There are two boots at level 40ish with the exact same dex-based stats except for the set-bonus but there are no mnd-based shoes higher than level 26.

That doesn't make much sense. Is it supposed to be that way? Is it like this for other jobs at the other GCs?

It can't be city-affiliation as both guilds (dex: archer - mnd: conjurer/arcanist) don't belong to U'dah. I understand that it's just a selection of items and I don't request a full coverage from 10 to 50 for all jobs and gear slots but having two almost identical items for the same level and job and none whatsoever for more than 30 levels for another class is strange...

It's like this for other Grand Companies too.

e.g. in Twin Adder, some uniform pieces seem to lean toward one role, while another piece of the uniform lends itself to others.

I think this may force us to venture outward to look for pieces that don't have synergy with our role/job.