Is there any point in penning down my thoughts even though I do not want to create a blog or keep a diary?
Once in a very long while, it’s as if I am struck by something and I feel like I remember my whole life. The thoughts come rushing in and I find myself jumping from one thought to another. Then the next day comes and the feeling is gone and I quickly dismiss them as the ramblings of the mind.

Only for your descendants. I have some papers concerning our Mennonite ancestors coming to Lancaster county in the early 1700s. They were written by an Episcopalian minister in the 1930s and some of his comments reflected on the political thinking of the day. It was fascinating reading to me, not only as a descendant, but also from a history point of view.
Sure — you can look back and see how you’ve changed and grown over the years.
Use a recording device.
Seriously. They’re indispensable for me in my writing.
Perhaps you should pin them down and write them on napkins to hand out to strangers on the street.
No seriously, everyone has random thoughts. But only pin them down if they’re really very good.
It is very therapeutic and can help materialize your ideas when you put them to paper. If you have the urge, go for it!
Look at it this way, how much would you like to read a diary of your great grandfather?
what?
"I write because I don’t know what I think until I read what I say"
William Faulkner !!!
I’d say that it’s not going to do any harm to write down your thoughts, and it might do some good. Short of a couple of sheets of paper (or a few electrons on a computer screen), what do you have to lose?
You never know when you may want to refer back to a journal for an important date/event from your past. I’ve kept a journal of my life for about 20 years and I’m glad I have them.