Third-party APIs/tools exist for several reasons, and are generally used for those reasons. Never using them on the off chance that support for them stops is a little extreme when the benefits far outweigh the downsides, imo. In particular, utilizing such tools is often drastically more convenient and efficient for developers than not. Furthermore, in the case of modifications for pre-existing software, such as Terraria, which does not itself provide a framework for modifications or plugins, the use of a third-party API is almost necessary if a developer wants their modification to be compatible with certain other modifications without the necessity of making and maintaining multiple compatibility patches.
While I mostly agree in principle with keeping third-party dependencies to a minimum for software development in general, such dependencies are practically essential in the case of mods or plugins for software that doesn't itself provide such facilities, as I mentioned above. It is not bad practice by any means, and in fact, I would personally contend that refusing to use such tools when they are at one's disposal and one has a need for them is incredibly inefficient and far more so bad practice than using them is. Imagine writing a login script in Lua and getting to a point where you need to run password data through a cryptographic hashing algorithm such as SHA-2 for secure password storage and for checking password inputs against the stored hashes. Would you seriously re-invent the wheel and write your own SHA-2 implementation from scratch just to avoid dependencies, or would you use a pre-existing, well-tested, third-party library designed for that purpose?
Granted, making use of third-party APIs/tools/etc is a trade-off. You get more convenience and greater efficiency at the cost of a certain amount of the surety of being able to keep using the same code in the future. Personally, I think it is a fair trade-off, especially when writing one's own implementations for certain things can be a drastically more significant time sink than simply adapting one's code to a new API should the one that was once used lose support.
But irregardless, I'm waaaaayyy off-topic, lol. XD The fact stands that tAPI has not been updated and will not be updated, and so far, neither TModLoader nor Prism have all of the tools needed, to my knowledge, to re-implement this mod, nor do we have official modding support as of yet, so we will probably just have to wait a good long while on this beautiful piece of work making it's way to Terraria 1.3. ;w;