I agree to an extent, but when you walk into your demense and everything you've ever summoned is there waiting, Home Turf doesn't mean much. Especially when your Demense is a representation of your mental landscape. If.your fleeing a battle that isn't going to be a fun place. That's part of the flavor bit though. However I've been looking at it as simply storage space. You can send your summons there, pull them from there, but going there yourself (physically) isn't a constant option. At that point Balance wise (and why most wizards don't summon like this for canonical purposes) it makes sense.
Lastly, any extraneous prerequisite is a balance thing. Sure it doesn't affect base power level, but it hurts customization, slowing down advancement. It still affects the class balance. Much like wizards needing the sight/soulgaze before taking lots of refinement.