Right or wrong, if consumers have the choice between a thinner, lighter laptop with better battery life and a more clunky laptop that is easier to repair, most appear to be choosing the former over the latter.

Consumers have very little choice. Especially with Apple, which releases whatever it wants and people buy it anyway. But with laptops and smartphones and other electronics, the "choice" often is that some phone operator or big electronics store chain randomly decides it's "Thin Device Era™" or something, and discounts a particular subset of devices. And people don't wait forever to buy a new device, they usually need one "right fucking now", so they choose from what's available.

The two are not mutually exclusive. I don't think gluing everything together is purely engineering decision.

Glue allows them to attach battery to the body. Macbook's battery is not single piece, rather is few batteries connected with each other shaped in a ways that allow them to fill all empty space within the body.

Some other current models achieve this in a different manner, with a molded cage that holds the individual batteries in place throughout the body but can be removed.