I honestly don't want any system where we can keep leveling the neck, at least for power. If anything, I'd rather see levels beyond a certain point be purely for cosmetic rewards. Maybe a couple FoS that give a title or transmog or something, perhaps it gives a currency that can be spent on a variety of things.
Technically, Vision's minor increase both the CDR (~.3% per level) and the SUPER TINY versatility (96 at HoA 69 for reference) you receive with each level. The catch is, the CDR caps out at 25%, and at 70, you're already at 21%. After your heart reaches 80, you're already at 24 out of 25%, and you're done in another 3-4 levels. After that, you only increase the versatility, which goes up at an incredibly slow rate.
You will hit the 25% CDR cap easily and naturally, and beyond that, the Versatility increase is so minor you wouldn't even notice.
Once you do the quest chain to unlock the Essence system and get your first essence, your heart is automatically boosted up to 35, as well as giving you all the Ilvl's that Champs rep used to give you. At 35, until around the early 50's, you only need ~1k Ap for a level.