Well you were replying to a comment about why we foraged for them before salt broski. Doesn't really make sense to bring up the price of something that wasn't isolated then.
I'm skeptical of any food that humans only started eating since the industrial revolution, including those that are derivatives of or isolated compounds of real food. Mostly the effects on our bodies are not well studied. I haven't specifically read studies on msg though.
I mean, foods like soy sauce and yogurt and sauerkraut predate industrialization, but are very processed. I wouldn't worry too much about MSG in particular, since it is also mostly made by fermentation:
You wouldn't choose to do manual typesetting (or copying books by hand!!!) today either versus alternatives.
If you're _just_ looking to add umami flavor to a dish today, you'd be crazy to pick foraging for wild mushrooms over Aji no Moto.