When I thought about the same question, firestarting with sparks seemed to be quite backwards and obsolete for me. I tried it for the toy value of it anyway. I found that it´s a pretty effective method and the tools are really robust. When you light a fluid (e. g. a Trangia stove) it´s even safer than a match or lighter. I many cases I prefer sparks to matches now.
I carry a ferrocerium rod that takes less space than two matches and can´t leak on my keyring. A similar rod is used up about halfway and already lit about 80 fires. That simply can´t be beaten by matches or lighters.
The usefullness in adverse conditons or as backup has already been pointed out and I second that.