Emojis exist in Unicode because people have written emotion-face pictograms inline in text documents (even before the advent of computers!), and Unicode needs a way to encode those existing documents such that one ":D rotated 90 degrees" is machine-readably-identical to another ":D rotated 90 degrees." For the sake of e.g. screen readers, sentiment analysis, etc.

But there's no reason that said pictograms need to have a rendering like anything more than what people would draw them as on paper. The Unicode ellipsis exists to encode the separate intent of "writing an ellipsis" from just writing three dots — but it's still just rendered as three dots.