For my pedal designs I’ve opted to omit the battery compartment for several reasons, none of them directly relating to sound. In no particular order:

• Batteries are environmentally unsound. Batteries contain acid and heavy metals that end up in landfills, in soil, and in the oceans. All my pedals are built with RoHS compliant parts; batteries don’t make sense.
• Batteries are rarely needed. Given the ubiquity of 9VDC center-negative power supplies, batteries are, mostly, unnecessary and for those times when you require a battery, there are external battery options available (we use the Joyo 5 in our testing). 
• Batteries are unreliable. My pedals are built specifically for the professional musician and pros cannot risk battery failure.
• Batteries become an ongoing cost; it doesn’t make sense to replace a $3-5 dollar battery after every few hours of playing.
• Batteries leak. Everyone I know has had the same experience: you open up a pedal that’s been idle for many months and see a battery that’s leaked inside the compartment (ugh).