Here are my thoughts as a one-time employee of a web hosting company; I built their DNS control panel for customers and their overall order placement and customer management API.
I think that the API access you offer is truly a great innovation in this space. I don't currently have a use case for it; have you thought of any that you could share? Programmatic creation of subdomains?
My criticism is that you need to properly answer the question of, "You're a startup; how do I know that you'll be here five years from now and my domains won't end up in purgatory somewhere because you go out of business?" Part of that echoes what nlh says below: It is not a good thing that you are advertising that you are 18. Rightfully or wrongfully, that works against you.
Yes, programmatic creation of subdomains is one. Another potential use case is domain-based apps. NameTerrific will roll out OAuth support in the coming weeks so developers can control their users' domains through NameTerrific. So you can help a blogger point their domain to a blogging platform programmatically, for example.
Also, you can create a health check program that automatically drops unresponsive nodes from a round-robin DNS-based load balancing record set.
To address your concern: eNom handles all registrations currently. If NameTerrific doesn't respond you someday (I'll make sure it doesn't happen), you can claim back your domain at eNom and then you can transfer to anywhere else. The domains are yours and never ours.
Regarding the age: I recognize that being a problem now. But there's no regret. I've done what I need to and I'll prove myself with time and results.