apart from the normal 'you gotta help! we're completely incapable of utilizing the equipment and defenses you graciously provided us with to even a fraction of their potential!' problems, they are just too buggy.
when i first discovered settlements, i was psyched. i spent a decade in the u.s. army, airborne infantry. planning and implementing defenses is fun. my first few settlements were pretty awesome. 360 degree coverage with interlocking sectors of fire and obstacles funneling aggressors into the apex killzones. deadspace coverage as well. i show up to defend, and see that the bad guys have bypassed my obstacles/crossed a wide open field while my turrets were apparently taking a union mandated break. sneaky supermutants/ferals/gunners/raiders/synths.
then there's the ever popular 'no-show' invasion. i gotta go running through the weeds to find them, or take a 3 hour nap. and sometimes, that doesn't even work. today, i fought off some synths, and 1 of them apparently ended up inside the foundation of my main structure. i gnashed my teeth and started pulling up the floor. the synth fell through the world. 3 of my settlers went after it. ended up failing the defense, and the settlers are gone forever.
and what's with animals/creatures attacking my crops? i show up to spectacle, and there's a mirelurk just doin dirt to my carrots. that's cold, bro. so malicious. i mean, they're in the ground.
if i make a new character, there will be 1 settlement. it will not be a happy place. since they will complain no matter what i do, i will give them plenty to complain about. after i lure about 20 of them there, i will scrap the crops. leave them with 1 carrot. they will get 1 water pump. not like they are gonna wash their faces/fingernails anyway. i will leave 1 sleeping bag in the middle of the road. i will take everything they own. they will walk around in their underwear and bare-knuckle boxing will be their only defense. and when the message pops up on the screen that they are under attack, i will smile sardonically and walk the other way.