Gecko zzed is good. Gecko zzed is wise.
He sums it up nicely. One of the biggest uses for EQ is to "fix" things so if you're happy, there's nothing to fix! I must say that, when I record, I try my best to get the sound exactly as I want it as I lay the track down purely so I can use the least possible processing later.
However, as has been said, where EQ can come into it's own is when you're trying to make multiple different tracks "play nicely" together. At that point, even if each individual track sounds great on its own, a bit of EQ can stop them from fighting for space in the mix with each other. As Gecko has said, it can also become a creative tool to take a sound and change it substantially to suit a mood or style you're trying to achieve.
On the remedial side, another use is to compensate for inaccuracies in microphones. For example, I quite dislike the presence peak on an SM58 so, if forced to use one for whatever reason, know exactly where to go on the EQ to tame this. Similarly, proximity effect can cause too much/too boomy bass and a bit of EQ can sort this out quickly.
In my case, an additional use of EQ (since much of what I do is for playback in a theatre setting) is to make my recordings sound better when I consider the acoustics of a particular venue. I can bring up frequencies that are fighting with the rumble of *&@! moving lights or whatever.
And, in truly live mixing, EQ is both a tool to control feedback and a way to make amplified voices come closer to matching the original on a sound system.
So, although a useful tool, no, EQ is NOT always necessary.
Bob