I wouldn't call it crucial so much as a nice added touch, even radio shack did it on the ends of their pre-cut speaker wire. If your system is going to remain relatively static once connected, i've probably caused you a bit of ado about nothing with regard to tinning the ends.
A bit of care to err on the side of caution regarding loose strands will likely be sufficient.
Many of us hobbyists and enthusiasts end up rotating a lot of equipment in and out of our systems, and this is where steps like tinning the ends of bare speaker wire will really come into play.
