I usually insert emoticons using the insert images button, but since there'a lots of it in all sizes sometimes it doesn't look beautiful to see in the blog, with a small font and a big emoticon.

This, actually, is my standard experience with graphical emoticons: they are almost invariably larger than the font, so inserting them makes the leading uneven, which drives me nuts. So if this suggestion does get implemented, I'd really hope that the emoticons used would be SVG, and carefully calibrated not to exceed the space used by the font.

That being said, I don't see any good reason to deny graphics lovers the opportunity to use graphics as long as there is accommodation for screenreaders, and for those who simply want to be able to turn the images off.

In the meantime, one_step_will_take_me, did you know you can control the display size of your images by specifying the height and width?