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Adding subtitles to videos has been a really hard problemFor whom? When? There are decent applications for this, some of them even free.
I've seen fantastic fansubbing work, with beautifully rendered, animated subtitles; and that was already years ago.
Making basic SRT's is easily accomplished in a rudimentary program like the old Subtitle Workshop by URUSoft: http://subworkshop.sourceforge.net/
(Looks like those guy have been active lately and have some new stuff out: http://www.uruworks.net/index.html )
Burning subs into a video is easily done with a ffmpeg one-liner (using its "libass" renderer or whatever). (Someone nontechnical may need help putting together that oneliner, but after that it's just repetition.) It's generally a bad idea; don't hard sub if you can avoid it and make the video available without the hard subs.