Maybe some players like the current Summoner, but it completely disrupts the balance of the Caster role.

It belongs to a specific category where frequent spellcasting is expected, ideally with special abilities to move only when necessary.
The old Summoner fit this category because it had no excessive mobility and could build up 4 stacks of Ruin IV and 4 stacks of egi-assault to move or during Phoenix Trance,
much like the current Pictomancer who can accumulate 5 stacks of White Miracle and has 3 Hammer hits for movement.

This is what every caster should have in their kit—not resembling another category they don't belong to, like a Physical Ranged DPS.
Having constant mobility makes it impossible to balance properly, it will either be abnormally low in DPS or too good, leading everyone to play it at the expense of other casters because it's no longer a true caster.

The fact that the Summoner is easy isn’t the problem; the issue is that it no longer respects the category it belongs to and the job doesn’t even have resource management.
The demi-summons are basically copy-pastes of each other, so the rotation lacks identity.
Each summon needs to be made unique, but currently, they aren't—except maybe for Ifrit.