In fairness to the TypeScript team, their position on this subject has been consistent for a very long time, since well before Deno. They do not see themselves

In fairness to the TypeScript team, their position on this subject has been consistent for a very long time, since well before Deno. They do not see themselves as being in the business of rewriting import specifiers because there's just too many things that different groups would want them to do. I'd also like them to support importing .ts files and rewriting those imports to .js, but given that they've been clear about their position I think it's up to Deno to solve this without forking the ecosystem.