The reasons are multiple.
First, i like how pedals behave in general as they're kind of universal in terme of level (except in modular, but I avoid getting into modular) : I mean they work in most situations without caring too much (instrument/line input, insert etc).
I happen to build axoloti-based effects for people, and i'd like to fix the dB drop which has been much discussed in this forum. I can't presume the way they're gonna wire it (ie in series or parallel).
Another example would be to include a true bypass switch in the design without any strange surprise in volume...
You're right about the input gain object. It works fine by adding a basic audio buffer (like Klon for instance) before it with a +/- 1Mohm impedance and add some dB. And why not, an input gain control with a nice clipping led, or a pad switch.
Still it doesn't fix the output level, which, again, is talked many times here. I understand the software side is OK, but has to see with the limit in p-p voltage. The idea would be to boost it a little. Just some dB.
That's where i face my limits in circuit design, and especially on the power supply side. I'd like to make a simple post-amp, opamp based (why not transistor), which could be driven with the same 9v supply i'm using to power the axoloti. Put a trimmer, test it with a sine wave until happy, et voilà.
Until now i'm getting some noise / whine. There must be an easy way to do it....?