Is there any way to revert to text boxes? or at least turn them on?

No. This is a complaint that many have had over the years. You need the floppy version to play with text.

Well, then it would be nice to include both the CD version and the floppy version (if that's even possible, of course)...

I agree. I think the reason they didn't is that the floppy version of KQ5 had some rather annoying copy protection scheme which would've needed a crack to bypass.

Hehe, I own the CD version myself (part of Roberta Williams Anthology), and the dreadful voice acting is the single reason I haven't ever played it more than an hour.
I definitely agree that offering the disk version as well would be a good idea, even if the only way to do that was to include a cracked version.

Yes, I really wish the non-talkie version was available. I played the floppy version when I was growing up, and I, knowing what a great game it is, can put up with the terrible voices now to play the game. However, I recently recommended that my wife play some of the KQ games and she is having a really hard time getting into 5 because of that...I know if it weren't for the voices she would love it. At least in KQ6 they gave you the option to turn it off, although the voices weren't anywhere near as bad as 5.