There are many people who watch Star Trek not because it is an interesting TV show, but because it inspires them to, literally, reach for the stars. I think the title song, while not necessarily a good scifi piece, is very good at conveying the feelings these people feel when they look up at the stars... inspiration and the drive to explore. Enterprise differs from any previous Star Trek in that it is very contemporary, very close to our time, and very visible to visionaries. It is something to reach for in itself, and it would be an injustice to not have a similarly inspiring song.
The lyrics talk about enduring and having what it takes to get to the final frontier, and I hope the show's producers will do the same and ignore the naysayers, keep the title song, and perhaps inspire future generations of young explorers.