I'm not following the idea that she committed suicide but did it in a thoughtful way so that she wouldn't be found at home, or found right away.
Let's just say that's the case - she committed suicide in such a mysterious way that no one is sure whether it's murder or suicide. How is THAT considerate of her family? Okay, I'll commit suicide but kinda make it look like murder, but it won't be murder, so family and friends will never know what really happened....?
No one said that she did a good job. The theory is that the text message, doing it while she should have been at work, leaving confusing evidence in the car, and then walking 1.5 miles to a culvert would make it unlikely she would be found before she had passed away, and maybe less likely to be found.
I am not sure that the motive is necessarily to make it easier on her family. We see people go to far far greater lengths to be not found ever, and a missing family member creates a huge amount of stress and pain on the family. It doesn't always make sense, in many cases the thought process is not rational.