Your thoughts are all personal opinion above and taken with a grain of salt
Type in "Leg raises hernia" in google for your education. No weights necessary to cause problems.
All of my thoughts are regurgitated information I've copied from experts in the field from the books I've read. I try to resign myself to keeping no opinion on the matter since I'm not a sports scientist and certainly no expert in the field.
And neither are you.
I study the pros who take athletes to the olympics. Take Poliquin for example. If he says X, well I'm going to start saying X. Why? Cause he knows his sh*t.
What the guys that I'm studying are saying is that crunches are bad for performance, bad for your back and even bad for getting those abs they're 'designed' to get you. Crunches and all of their variations with all of their gizmos and gadgets are worthless. Don't do them.
Type in leg raise hernia into google? Okay, so don't do leg raises. Type in "man getting hit by bus when leaving his house." Okay, so never leave the house.
With every workout, there are risks. Nothing is 100% safe. Especially Squats, which are a highly technical movement. Deadlifts are much safer.
All I know is that many martial artists and gymnasts use them frequently. These guys are often the epitome of athleticism, having the body we all wish we had.
Of course, don't *only* do leg raises for the next 50 years, every single day, with 10000 reps each days without pause. Yea you might hurt yourself. Try some variations.