I understand Unicode and its various encodings (UTF-8, UTF-16, UTF-32) fairly well. UTF-8 is backwards-compatible with ASCII and only takes up the extra bytes if you are using characters outside of the 0x00-0x7F range. E.g. this comment I'm writing is simultaneously valid UTF-8 and valid ASCII.

I'd like to see some good evidence for the claim that Unicode support increases memory usage so drastically. Especially given that most data in RAM is typically things other than encoded text (e.g. videos, photos, internal state of software).