Yes, I think "too modern" is exactly the right phrase. Unfortunately, trends such as ending names with "lyn", having an "ae" in a name and/or a Y in a name is very modern and will therefore make a name seem dated, in my opinion.
In 30 years time, if you meet anyone called
Braelyn, Braydyn, Bayleigh etc. etc., you'd just know they were named in the late 2000s/early 2010s, because the names were never popular before and will probably go out of style relatively quickly because they're too common.
Another reason I tend to dislike these names is that, because they're not established, well-known names, there are a lot of different, equally-common spellings and so people are bound to get it wrong all the time. For example,
Braelyn could also be spelled Braylin, Braelynn, Braelin, Braylynn, Bralyn etc. etc. None of these names are "legit".