I voted that I "need" it, but really I don't guess anyone "needs" much of anything effect-wise. With good practice and technique, good players can make passable covers of songs with whatever stuff they have available.
That being said, I play mainly in church with IEM's/click tracks. Tap-tempo really helps with precise timing/tremolo picking, particularly on the Hillsong stuff.
I can do ok without it but I really like it. I use more delay than reverb, and in a 3-piece situation it really adds a lot when subtle repeats are there in sync with the music. A lot of my patches don't sound like they have much delay, you don't notice it. Till I turn it off...then it's like "what happened?".
Having tap tempo allows me to use the delay more prominently and creatively. Without it I only use it as atmosphere. Oddly I find that for atmosphere it sounds best at the historic max bbd times (around 300 ms and 550 ms). Just what I am used to hearing on records I guess.