I used to have that "my amp is essential" feeling, but sometime in the past decade or so it totally shifted.
What happened was, I started playing Gibson-style basses that have a big growly midrange and a subdued high end. First I got the Greco bird clone, then I got the LPB-1 which is still my favorite sound of the bunch, though lately I'm playing the single-pickup DC tribute junior a lot.
All of these, especially the LP, give me a direct sound that I like, even with no EQ. In fact, it's almost hard for an engineer to screw it up, even if I dislike their EQ choices.
I used to hate going direct, because I was playing through 12" drivers that had the typical huge presence peak and no treble above about 5k, like a guitar amp; and I was playing an Ibanez with Alembic active pickups to get the brightness I wanted, which meant that if I went direct there was suddenly a lot of very obnoxious sizzle in the top octave and it just sounded awful. I hated bass cabs with tweeters, especially because so many of them frankly had terrible tweeters so they weren't even good full-range speakers.
So I relied on the speakers as a big part of my EQ, and would always beg the FOH guy to mic my amp, and if they refused (which they often did in the low-end clubs I played; those guys are paid almost nothing and they just don't want anything that adds hassle to their night) ... then I would have to warn them about the distortion pedal and beg them to turn down the treble, which just sounded bad.
Life is so much easier now and I like my sound better.
My current preamp (Genz-benz shuttle) adds a little growly saturation, which is like the icing on top - I love it, but I can get by fine without it, and there are lots of other amps and/or plugins and DIs that work well too. I'm thinking of trying to find a pedal that does something similar for me when I go direct or use a house amp.