The first reason is because if we supported ts features that require transformation (such as enume) we would also need to support sourcemaps, so in the first iteration I decided not to, to avoid being overwhelmed. Right now we replace inline types with whitespace, so locations are preserved. We plan to add those features, probably behind a flag at the beginning. We need to move in small steps and think very carefully, every decision could make a huge impact on the ecosystem so I decided to start with the smalled subset possible.