Like, I kind of get it that we got lots of focus on young Isaki (due to it being on Ganta's POV, so once we change see him directly, it's when they are adults. Buuuut, if there's something that makes me angry about time skip endings is, not showing one of the main leads' faces... especially if they happen to be women, lol.
On one hand, I feel the authors want to hide them due to "innocence" and the like. There's this other SoL manga that I read that basically made the same thing at the very end (doesn't help it is actually a "pilot" of things to come in a sequel/spin-off that happens further in the future from the actual series this was closing of), and I KINDA get why the author did this (there's a subplot that this character's adoptive relative hasn't seen FL in years), so, is it a metaphor of not showing FL because the new ML of this spin-off series has an specific image of FL's face from the time they both were younger? Similar for the readers as well? Something something about not staining the "innocent" image we have of the FL?
On the other hand,
I hate it 
.
It's like. Building this sense (for the readers) that fictional (and also non-fictional) young women aren't meant to "grow old" as the ML. We get imperfections, wrinkles... and sometimes, just sometimes, some of us stay baby faced. And it's kind of unfair? Ganta sure looks adult, at 30, but he remains
baby faced with all that stubble! Isaki deserved a few close up shots! Even if we are told that she looks healthy as much as she has been handling that for years, you know?