They look adolescent because they have clear complexions?
I think a lot of the complexions are unflattering. I'm not a big fan of freckles and I don't particularly like how, I don't know, splotchy? some of them are. I don't think the ones I choose make my elves look particularly young though.
The first picture in the topic does look kind of young to me, but I suspect that has more to do with the big eyes and the perspective of the shot.
Well not to spin my own thread off topic, but dealing with complexions is something that I have noticed going all the way back to Mass Effect 1. From all three Mass Effect titles, and all three DA titles, I have noticed that the created males all have varied looks. Soom look young, some look older, some look like D&G Models, and some look like grizzled veterans. Then with the females they are either super models or young looking. You see VERY few older female Shepards/Hawks/Inquisitors/Wardens and you see VERY few grizzled female Shepards/Hawks/Inquisitors/Wardens, despite the fact that the lore could totally be legit for such characters who have a "hardened" look.
Like I said, I think a lot of it has to do with out society views beauty in terms of women. With men, they can still be very sexy and be sex symbols in their 40s, 50s and even 60s. With women, that is normally reserved for the 20 somethings and 30 somethings. Yeah, society today at least does recognize the sexy nature of women in their 40s and up, but not as nearly at the same rate they do men. Also men of any age could have a "grizzled" look and still be sexy but let a female have that and they are too masculine. Just look at some of the reasons why people decided not to romance Cassandra.
With all that being said, I believe that is the reason why in terms of videogame RPGs, a majority of the women that players create have "youthful" appearances to them whereas the men have everything from youthful from all grey haired man with scars and wrinkles.