/splay can be very useful for creating various error/warning/etc sounds in scripts. It can be used to create specific notices to you when something happens rather than using only beeps. Etc. Yes, it's used more often for playing music or putting sounds into games and other non-IRC scripts. But, it is still useful for IRC-related scripts.
As for the DLLs... I have to agree that if you need so many and only need a piece of each one, then you really should go and make your own DLL to do those things. It may not be as fun for you, but then you don't have to deal with all those DLLs. That's your choice, though. But, if you choose not to just because it's not fun, you can't really complain that you have too many DLLs.
The ID3 tag editing could be useful... Most ID3's I've seen aren't correct, so it would make editing them much easier. And, it could be easy to script something to download all the appropriate information off the internet and automatically insert it into the tags. But, again, a DLL would probably handle this much more easily than trying to add such a feature to mIRC itself. And, I believe I remember seeing a DLL to do this already.
As a note on your logic... "mIRC has all these extra non-IRC features already, so why not add more?" ... At some point, we have to choose to make a line that isn't crossed. If we use that logic, mIRC will grow into a very bulky program that tries to do everything every other program can do. As far as I'm concerned, new features are wonderful... BUT, we need to add only the features that enhance IRC, make common scripts easier to write, or is needed by, or will be used by, a majority of users. If we start adding features just because we can, then it just ruins the program.
