I'm not the person you pinged, just a random person browsing help forums :) But here would be my insight on this one:
You certainly could post something like this as a suggestion if you wanted to. In my experience lurking in the suggestion forums, things like this have indeed been suggested before (if you want to find them, I would try searching through the suggestion forum itself - terms like "lineage," "lineage tracker," "family tree" etc. and sorting by most recent would probably yield good results). In fact, I think I saw one posted quite recently!
I want to say that not a lot of people tend to support lineage trackers, though I don't quite remember the reasons why. I believe it might just be due to taxing the servers, but looking through the actual suggestion posts would defintiely give a better idea on the "whys" of it than I probably could. I think the main reason might honestly just be that, while some people enjoy lineage tracking, it just not a tool that the majority of users would really use.
As for the economy though, I don't see it as being a problem there! A dragon's lineage very, very rarely influences its value at all, other than g1s. G1s that are pretty will certainly have a price hike over similar non g1 dragons, but other than that, lineage is a fairly rare and niche selling point. (And even with g1s, the lineage alone isn't enough to make it rare - lots, even the majority, of g1s go for fodder price.) The main other examples are folks that collect pure g2 imperials, descendants of specific dragons (namely the glitch dragon
Naomi and dragon #666
Ignis), and occasionally folks who like to grab children of progens. Again though, these tend to be niche interests and it can be difficult to find buyers who are looking for that kind of thing or who are willing to pay more for a dragon because of it.
So, more in reference to your original question, I would just say try not to worry too much about undervaluing a dragon! This is where Nightwind's advice of "a dragon is worth as much as a buyer is willing to pay" comes in :) Any price above exalt payout and the auction house floor is going to be subjective in the end!