I do pretty much the same thing: Drafts for starting most text, now on the Mac as well as my phone. On my Mac, I used The Archive for a while, but now I use the beta of nvUltra, which is also fantastic.
I’ve thought about using Drafts for more, but in the end, the database is what leaves me cold. I could switch from The Archive to nvUltra painlessly (and sometimes go back to The Archive or even nvAlt for one reason or another) because both just use plain text files. I can open a note in Marked to get a much broader range of Markdown, HTML and PDF options. I can run scripts on notes or groups of notes. Hashtags and some crude project metadata (all in plain text) let me connect notes in various ways, especially with some help from Keyboard Maestro, TextExpander and a little Python here and there.
I really like Drafts for creating text, and I’d be lost without it on my phone (though I also use 1Writer — again, with the same Dropbox folder of plain text notes). But I long ago decided that I don’t want to be locked into a single app, or have to export and reimport my data to get it out.
But as long as Drafts stays useful for creating text and doing things with that text through automation, I’m thrilled with it (and willing to pay for it, needless to say). And I’m happy it works for other people as a more comprehensive notes database, because that helps keep it viable!