I would disagree to some extent here. Some thinigs, such as improved sights and grips, add no complications to the gun while also allowing enhanced response IF your body and mind allow it.
Wow, I am going to have to go mark the calender that DA and I agree on something! Where is my thermometer. Maybe I have a fever, LOL!
Seriously, at one time, sights on a firearm were an "accessory" as were a safety (something of a crutch for those who could not aim a tube very well), trigger guard, detachable magazine, a sling, etc. Night sights are a benefit that certainly doesn't add an weight, but is a handy accessory. Some of today's "accessories" are tomorrow's standard features.
Just because it is an accessory does not make it bad, or good for that matter. It has to be something that is particularly beneficial to you that you know how to use properly.