Battery will never happen, they're no longer a singular thing you can replace but a multitude of inter-connected parts, each carefully positioned and glued in place. Why is this a problem? Apple will replace it for a nominal fee should you be experiencing problems, and if it's a dramatic malfunction, like the dreaded bubble battery, they'll often replace it for free.

Because having a user-replaceable battery is much more convenient?

Convenient for who? Apple's explained, over and over, that a removable battery is a no-go in modern laptops, the amount of material required to encapsulate it and dock it eats up tremendous amounts of space.

Most people would rather have a 14 hour battery that's not replaceable than a 6 hour one that is.

I've had a lot of laptops in the last fifteen years and the only time I'd ever removed my battery was to add memory or a hard drive simply because it was in the way. Maybe one in a hundred people actually care about having a replaceable battery.

And forward delete please. I miss it whenever I'm undocked and using the built in.

Fn + Backspace. Not as easy but that's the answer.

I know, I just get used to using the actual delete key when I'm using an external keyboard, so my muscle memory never kicks in fully to use fn+backspace.

That's what external keyboards are for.

I find the built-in style is fine for casual work, even typing documents, but for programming I love my delete key too much.

On the mini keyboard I find myself using ⌘X in place of Fn-Delete, it's a one-handed thing that's more convenient. If you have nothing in your paste buffer that's important it works out well.

I have a laptop which has all these keys though, in a 15" form factor. There's no reason Apple can't put these keys in (and they used to) - they just don't want to.

For whatever reason, Apple prefers to make a single keyboard for their laptops, regardless of the size. Even the 17" had the same keyboard.

Plenty of small laptops with a dedicated delete key. Don't see why Apple couldn't add one.

Probably because the overwhelming majority of people don't really care.

Those that care about a forward delete key are in the minority. They're also the type most likely to have some kind of highly personalized keyboard with very particular Cherry switches and keycaps.