A tincture from the seeds, if properly made, can be used for its psychoactive properties. The effects are subjectively quite different from LSD. Excessive dosage can be lethal indeed.
I experienced the effects of LSA as less mentally intense, more manageable, bit more decent and fine grained (visually) compared to LSD but quite extensive in auditive realms. I can remember listening to hours of acid techno that my brain on LSA made out of a buzzing refrigerator

Lethality can be solved by resolving the poisonous parts of the seeds by grinding the seeds, soaking it for 24 hours in petrol ether, squeeze out the ether and let the remains fully evaporate. You can then soak the ground, dry, ether-free seed in food grade alcohol, which makes an easy to dose, psychoactive schnapps which virtually eliminates the onset time you have to accept when digesting the seeds. Also, no vomiting before things turn colorful and magically moving

I think i got the original reciepe from an article off the erowid.org archives. A must-visit for every psychonaut.
Yes, Erowid is an important repository of knowledge and can be a life saver, however it's losing pace and not keeping up 100% with the new grey area molecules.
Incidentally, I got the same recipe from DMT Nexus, but I never actually used morning glories. I was planning to use it with some Hawaiian baby woodrose seeds I had lying around, but I never got around to that.
As you say, most lethal events are caused by substances other than the "interesting" alkaloids - things that can be washed away by suitable nonpolar solvents. However, the alkaloids themselves can be fatal too if dosed stupidly high: they have serious vasoconstrictive/abortifaciens effects and were the cause of several deaths in the past (when eating too much claviceps infested rye).