Why is gin still manufactured bitter taste?!

Fashions change?

A practical advantage to making it "dry" is that it's more versatile as a cocktail ingredient; you can sweeten up a dry drink, but can't unsweeten a sweet one. I don't like neat spirits - bad habit to get into - but as I drink English bitter beer, the few times I've tried neat gin, I haven't found it excessively bitter.

The period you are talking about was an embarrassing episode in the UK, both in regards to the devastating societal consequences of failed political doctrines, and the quality of domestic drinking spirits such as gin.

Throughout history, politics dictated the use or prohibition of gin. When the crown allowed untaxed and unregulated production of gin as a way to ensure spirits would not be imported from countries currently out of favor with the crown, there was an explosion of extremely cheap, extremely low quality gin. It was absolutely necessary to adulterate it with sugar to make it drinkable.

The earlier dutch gin was slightly sweeter than london dry, but not horribly sweet like "Old Tom" from the time period you state. Both dutch gin and london dry gin were made to much stricter standards than old tom gin.

To answer your question: when you were a child you drank as a child, there will come a day when you set aside childish things. Someday you will appreciate a man's drink- everything in it's season, my love.

Talkin's thirsty work, I sang for my supper now where' me martini dammit?

Try Dutch Jenever instead, that is what Gin was based on, and if much sweeter (especially some of the fruit ones)

Original gin was Dutch, London gin aint the real thing