- it can decrease performance
Literally the exact opposite, shorter variables names and inlining of functions at compile time increases performance

- it makes debugging in prod harder
that's why you generate a map

- it wastes time to configure it
literally 2s to include bukkit as an external dependency

- it wastes money on buying software
i don't know what this means, if it's talking about buying an obfuscation program than the best one (proguard) is already free

- it doesn't fully protect your software anyways
sure but that's like saying you want to go to war not wearing a helmet because the helmet doesn't fully protect you

- it makes your software harder to maintain if you chose to abandon it
but the point of obfuscation is to deny modification to the source and if you want to abandon it but allow the public to continue it then you do something called releasing the source coode

- it makes it harder to add my own modifications
what, it's a compile step not a modification to your existing code