Nathan is essentially right in his response (thanks!), although I’d like to point out that using AxCrypt 2 portable does not require installing it, just like having the old-style “self-decrypting” file does not require you installing it.
In fact, the only difference is really that you now need two files instead of one. AxCrypt-2.1.NNNN.exe + Whatever-ext.axx.
Anyway, since this question does keep popping up and while we’re still not planning on implementing it for the reasons mentioned in the blog post referred to by Nathn – we’re still interested to achieve similar benefits for similar situations.
So, if you just please explain just how you use the self-decrypting feature, and just what it is about it that is so attractive, perhaps we can come up with a way to satisify everyone?