Technically, they did lower its BV.

4Lz actually had the second highest BV drop percentually (first was 4A). 4F not as much, though, surprisingly.
I noticed the 4F was not as much, but IMO, the value of a 4F in the last system was just sliiightly too low. In the previous scale of values:
3F = 5.3
3L = 5.1
So, a 3L was 96.2% the base value of a 3F.
4F = 12.3
4L = 12.0
So, a 4L was 97.56% the value of a 4F.
If the 4F had a been given a BV 12.5 (instead of 12.3), the 4L would have been 96.0% its value, which is way closer to the base value ratio of the 3L vs 3F. Then, take the 12.5 BV of 4F and reduce it to 11.0, that would have been a 13.6% reduction -- which would have put it somewhere in between the reduction of a 4Z and the reduction of a 4L in the new SOV.
As far as the 4A having the highest percentage drop, that's not as much of an issue as the 4Z percentage drop, because there are no men are actually doing a 4A, and none have attempted it to date. So as it stands, the rule does not benefit or hurt anyone. I get some skaters are hoping to try a 4A, but are people honestly going to care how many points they got for it more than the actual achievement?! On the other hand, there
are men who actually reliably execute the 4Z and rely on its base value over the other quads. Some skaters can win with easier quads because of their high PCS, but other skaters with less PCS rely on the base value of the 4Z and 4F to compete with them, and now that's been reduced.
Notice how there's no longer such a huge discrepancy between a 4T and 4Z. Before it was 3.3 points difference, now it's only 2.0 points difference between them! And that's considering that a 4Z was already rather low in value to begin with relative to a 4T:
Old SOV:
3T was 68.3% the value of a 3Z
4T was 75.7% the value of a 4Z
New SOV:
3T is 69.4% the value of a 3Z
4T is 82.6% the value of a 4Z
For people griping about the low value of a 4A which hasn't even been
attempted, IMO, there's more to gripe about the 4Z which guys
actually do. Funny enough, if the 4T were proportional to the 4Z the way a 3T is to a 3Z (69.4% of its value), then the 4Z's base value should be 13.7 (which happened to be slightly above its old base value). Clearly the ISU is bunching elements more, even making the triples closer together, and they've done the same with quads - essentially mitigating the advantage of higher level quads. But until someone actually does a 4A, the guys reliably doing a 4Z are the ones getting hurt the most by this.