Indeed we should, but here's the catch: where is the
button in this screen capture:
It is a serious deficiency of the board software that there is no basic Post Reply button at the bottom of each post, and that the Quote button is so dominant. I would shrink the quote button to the size of the multi-quote button and add a Post Reply button the size of the current Quote button.

I would also disallow quoting entire posts, and I would disallow quoting images. I would modify the quote button behaviour such that when you select some text before clicking it, only the selected text would be quoted.

Another issue is the Quick Reply feature. There is a checkbox to quote the post, but unless the member switches to advanced mode, there is no way to change how much of the post is quoted. So I would remove that checkbox.

Finally, I would prohibit quoting any part of the last post when there are no intervening posts. Overtyping makes this a technical challenge, but not an insurmountable one, IMO.

Many posters don't understand the implications of over-quoting; some understand but can't be bothered to reform because the software doesn't make it easy. Assuming IB doesn't get a kickback from mobile data plan vendors, it is in everyone's best interest (save the ISPs and similar that charge by volume) to evolve the software in this fashion, so I don't understand why it hasn't been done.