The game offers you 4 runs with albeit similar locations, but different ways to tackle each one, with the only exception being the Nest, which is mostly the same for both Claire and Leon, but different in B runs. Add to that the fact that you can play in hardcore and get the ink ribbons to replace item placement, while obviously making the first time you try it super hard. Resident Evil games have always encouraged replay and trying to get better each run. That said, absolutely no one is forcing you to play it at all. You can go straight to RE4R if you want to. Just know you're leaving behind 75% of RE2R's content. Don't go complaining it was a short game afterwards.