This answer mentions says that the stripes on the tallis are reminiscent of techeilet. Now, we have a few different dyes that claim to be techeilet, which many people wear. Usually, talises with techeilet also have the stripes. Do they need to have them? If so, should the stripes on the talis match the color of the techeilet string?
the stripes are not "needed" they are a Minhag. accordingly, talisim were not origionally striped. I take the liberty to guess that manufactures of todays talisim with techeileit that have stripes as well, are simply producing it according to peoples perceptions of what a talis should look like. In regard to the color, i'ts interesting to note the the Hassidic sect of Belz has in recent years changed the color of the stripes on their non-techeilet talisim to a more blue/ light blue color- presumably to more closely match the original color.