Everything i've found wrong with this game so far.

[Enkidoh]

Yeah, if a mob agroes you with your summon out, the summon will automatically attack the mob, but if you get too far away, the summon will automatically dismiss. They don't dismiss for simply falling behind.

As for some of your other problems with the game, there are methods in SE's madness:

3: Why doesn't endgame gear have materia slots?

Well, endgame gear is supposed to be 'unique', unlike the majority of gear up to that point which is mostly crafted. I would like to see some unique traits on gear though, as long as it didn't lead to a return of gear swapping in mid battle like FFXI had.

4: Players should be allowed to use mounts inside city walls.

No FF game has allowed you to ride a chocobo/mount inside a city, so this is actually traditional. Each city has their local aethernet for helping get around quickly so being able to ride a mount inside a city would be redundant anyway. Having said that though, in the last few weeks of 1.0's service players were able to ride mounts inside Ul'dah, but that was because of gameplay reasons - Ul'dah was constantly being attacked by high level monsters to help lessen the server load so it's likely all SE did was temporarily recode that section of the zone as an 'outside' area to allow enemies to spawn out in the open there, thus also allowing mounts to be ridden in there too. I doubt SE will ever bring that back though.

7: Lancers and dragoons should not be severely relegated to wearing pug/monk/archer/bard gear until their early 40s and unable to roll on numerous pieces of heavy
armor that their class is listed on as a valid wearer. i see casters have the same issue with dps/healer gear.

Why? LNCs and DRGS are not tanks, so why should they be able to lot on tank gear which a tank actually needs to do their job? There is also a traditional reason why DRGs cannot wear heavy armour - as it would naturally constrict their jumping ability for obvious reasons.