Emoji keyboard layout shows very few emoji at a time

Ubuntu 15.04 r224, BQ Aquaris E4.5

1. Switch to the Emoji keyboard.

What you see: Only 18 emoji are shown at a time.
What you should see: Many more than that.

In contrast, the Emoji keyboard on:
* a Nexus 5 shows 21 emoji at once
* an iPhone 5/6 shows 40 emoji at once — more than twice as many, in less space.

There seem to be four reasons for this inefficiency. In order of importance:

A. The spacing between and around the rows is enough, in total, to fit an entire extra row of buttons. (Part of the spacing is because the keys have curved borders, apparently imitating some hardware Emoji keyboard that doesn't exist.)

B. Most of the bottom row is taken up by a space bar, which is seldom relevant when people are typing emoji.

C. Scrolling does not use the standard flick gesture. Instead it uses two dedicated buttons that, as well as being inconsistent with the rest of the OS, take up space on the keyboard.

D. The keyboard has a “?123” button that is redundant with the button for switching layouts.