It does matter. You can multiply by a power of 10 in the implementation, to stick to integer representations.

But it's a terrible idea to expose that change to humans at the nominal level, because, unlike the code, it results in countless references to update. And messes with their minds unnecessarily.

Let's say I bought 1 BTC and made a blog post about it. Now, after the split, I own 10 "new BTC", but someone reading the blog will read that I bought 1 BTC and won't know whether it refers to new or old BTC -- unless I update the blog post to clarify that.