I am still using my android device from 2.5 years, but the battery is dreadful and it's not lasting 12+ hours anymore without a charge.

they need to have self replaceable betteries in common sizes like they do for other devices.

The reason we don't see phones that last that long is that it's hard to make a profit. Companies would need to charge a lot more per phone before they even think about it.

I like the idea but to make a profit companies would have to sell it on a subscription basis or charge a lot more with financing being part of the sale.

If you don't have any argument to support an opinion, you can always support it with "it's <year>". Or if you live in a very rich country, "in <country>".