Thanks for the feedback. I agree that there are things we can improve around sounds.
The main reasons for teaching the sounds is more to cement in the user’s mind each of the associations. Since our associations are arbitrary (e.g., ti- corresponds to “Timmy Turner”), it is necessary to teach them. Our quizzes, after all, just quiz on that association (Q: “What sound is Timmy Turner associated with?” A: “ti-”)
Now, we could just not quiz or teach sounds entirely, and have the user pick up on these things gradually through context, but I think that increases the barrier to understanding. There are only 72 sounds in total, and we teach them only as they are necessary (e.g., a less-common one would only show up as a lesson right before you are taught the corresponding character), so it only adds up to 7 days in total of lessons at the standard 10/day rate.
This rationale is similar to components as well. The components within Heisig, WaniKani, HanziHero, or any other using a similar mnemonic system are partially arbitrary, hence the need to teach the specific name that is used within the given mnemonic system. Many components have no “official” name, after all. And certainly no official English name.
However, despite all of this, we do plan on adding functionality to skip characters people may already know within the coming months. But we think teaching the necessary components and sounds for each character one wants to learn is somewhat necessary. Mainly because that is how the entire system works. It’s a necessary upfront cost, it seems.
Though I could see us allowing a user to mark certain components as “known” if they really already know them from another mnemonic system, but I don’t see us doing that anytime in the coming months.
While Pinyin can be broken down that way, what most people refer to is a Pinyin chart, which will not clearly break out the medial into its own category. This is what you will see on most Pinyin charts like this one or even the one on Wikipedia. As I note in the documentation page you refer to, most of our differences from “standard pinyin” are mainly of academic interest. In the same sense that many resources just have initials and finals, and some resources may talk about medials - all we are doing is slicing it a slightly different way to meet our ends. The most important unit in Pinyin is the complete syllable form, which we do not modify at all.
However, I do think that documentation page could be made much more clear and just give the TLDR of how our pinyin “chart” may differ from others but its really not important and we have a good reason to do so for mnemonics. Thanks for the feedback 
Yeah, just adding any sort of pinyin chart would be very helpful. We’ll definitely do that at some point! 
Yeah, we want to add bopomofo at some point for sure. I agree that Bopomofo is more clear in this respect. For example:
- Pinyin: qiong = q + iong
- Bopomofo: qiong (ㄑㄩㄥ) = q (ㄑ) u (ㄩ) + ong (ㄥ)
The way Bopomofo does it, where the medial is not “simplified” or “reduced” or however you call it, makes it clear that it should have that umlaut ü sound in qu-. Many foreigners don’t realize this because Pinyin drops the u and replaces it with an i here.
Like that documentation page states, much of our system comes from the Marilyn Method which is also more inspired by Bopomofo than Pinyin.