Summoner Changes

[Enkidoh]

That isn't the only reason.

In Final Fantasy XI, an Eidolon was basically a very powerful spirit being. Though technically a wild entity, that could cause great amounts of devastation if left to its own devices, with the exception of Bahamut, Odin, and Diabolos, they were largely benevolent creatures.

Primals in FFXIV are essentially vengeful gods of destruction. Nothing more and nothing less. The tempering process makes anyone who would summon them into their slaves. The only reason the player is immune to that is because of the Echo.

Summon monsters in FFXI were called Avatars, not 'eidolons' (which were the summons in FFIX and XIII). But you're right about everything else.