If SBD were $1, a vote would currently have the same value no matter when or where it was cast. It doesn't go to the same people but a $0.15 vote is always worth $0.15 to someone involved with the post. This does change that, drastically.
(The broken SBD peg does make votes more valuable when cast early under the current system, though that's obviously much less of a big deal now.)
Okay, but I find that irrelevant. There are many different and independent voters (usually) and how the rewards are distributed between them changes, sometimes drastically. The sum of all the rewards going to a group of different independent people is a number without relevance.
If you are concerned about the case where the author is the only voter (or perhaps that all voters are colluding in some manner) and is rewarding themselves for something that no one else cares about, then you would have a point, in theory. Most would find that irrelevant at best and undesirable at worst.
It is literally the value of the action of voting. It's incredibly relevant. In a larger sense it is the value of my stake, which is pretty much the most important thing here.