you could have said that about SSL or Unicode as well and you would be dead wrong, so, no, history proves very little in the mIRC world
if anything, the very dlls themselves are proof that K is "too lazy" (it's not really a question of laziness) to do it. Why implement something that's already implemented? Just to say "it's part of mIRC"? that wouldn't change much...
To actually make use of dialogs you need a script that has a dialog already setup, so you can assume someone is going to be downloading a script either way. It's not like SSL which should work "out of the box" without any scripts. So if you're already assuming someone will be downloading external (WHATEVER) files, why does it matter that part of the (WHATEVER) is a .dll? It shouldn't affect users. It *doesn't* affect users.
I'm not trying to say mIRC shouldn't improve its dialogs, but the fact that someone's already done it is a good reason why K shouldn't have to waste his time. In fact, you should be happy that such an external DLL exists, because now Khaled has more resources to invest in *REAL* problems that haven't yet been solved, rather than ones that have. There's no need to reinvent the wheel, especially when it rolls just fine.