The stated purpose of the project is "Icons under 1KB each". So embedding a 1KB license in each one would defeat the purpose.
Even if file size is not the main goal, embedding metadata could be self-defeating in other ways. If the license requires making the license available to end-users, would that prevent the use of asset pipeline optimization tools? (The motivation for using a permissive license is often to enable compatibility with general-purpose tools.) If the license only requires making the license available to maintainers, then why embed it in the first place?
My question is also about the other various instances of objections to MIT-licensed assets that were raised (i.e. in the article linked in the issue, as well as in other related issues). You're right that this specific case justifies minimal file sizes; maybe a modified/clarified license that only requires the copyright statement and a URL pointing to the license would be a better fit?
Re: asset pipelines, those would only be an issue if one of the "optimizations" is to strip metadata, which sounds an awful lot like a premature optimization to me.
On another note: most compression algorithms in vogue today can shrink the Expat license to less than ⅔ the plaintext size when base64-encoded. That's still hefty in the context of this specific project, but does still technically satisfy the letter (albeit probably not the spirit) of the license's requirements. Compressing the whole SVG file could almost certainly allow the icons to stay under 1kb, at least until decompressed (and an in-memory representation of that SVG file doesn't usually need to preserve comments).
The stated purpose of the project is "Icons under 1KB each". So embedding a 1KB license in each one would defeat the purpose.
Even if file size is not the main goal, embedding metadata could be self-defeating in other ways. If the license requires making the license available to end-users, would that prevent the use of asset pipeline optimization tools? (The motivation for using a permissive license is often to enable compatibility with general-purpose tools.) If the license only requires making the license available to maintainers, then why embed it in the first place?