Well part of my answer is why wouldn’t you mod? If you have a bass and it’s not quite what you want, then often you can change it.
Couple examples.
I have two ESP LTD Stream 204s. The body contouring is a little different, the wood on the fretboard is different, but I love the feel of how they play. Just so comfortable to me.
But they are entry level basses in the ESP line, and I’m not in love with the two band EQ, and the pickups were serviceable. They are both used, $300 range, so a refresh was an option when I bought them.
For the black stream, the pot on the EQ is wonky. Another factor is I am trying to purchase a new Stream 1004, which has upgraded hardware, but the date keeps getting pushed out. So she is getting the same pickup and EQ setup that an ESP E-II Stream has. So I will have the same sound as a $2400 bass for $600 total.
Yuki, the other Stream 204, looks like she was played a bit, and has some dings, than sat in a closet a few years. She cleaned up nicely and looks new, but for the corrosion on her electronics. So she got a new set, again she cost about $600 for bass + factory hardshell case + pickups.
My ESP LTD Surveyor 400 is another used bass, and had a EMG MMTW bridge pickup, which completely overpowered the neck pickup it had so much boom. So I changed that to a Delano, which in turn was overpowered by the active neck pickup, so I replaced that with a Delano. Now she is a passive bass, and sounds funky. Also has more tonal options as I added in a series/parallel switch for the neck pickup.
My Stream 1005 comes with EMG X pickups and an EMG EQ from the factory, she won’t get upgraded. She is fine as she is.
As for batteries, buy a 5 pack and put in your bag. If anything fails on a bass, it’s the battery. Have spares.