[Fury]

How about a sexp that reads a text file and displays contents on-screen? Additional arguments would control how the text is displayed. For example, you could have vertically scrolling text at specific coordinates at fixed width and length.

[General Battuta]

Well, I'm not sure what it'd give us that subtitles and training messages don't, except I guess scrolling ability...

[Fury]

Think of much larger amount of text, sort of like in-game fiction viewer. One could use it to display long credits at the end of campaign for example.

[General Battuta]

I have a feeling it would be a ton of work for relatively specific gain.

[Goober5000]

I have a feeling it would be a ton of work for relatively specific gain.

This.

Plus, it can be done with existing sexps.