Is it? Well comparing 30 km range to 500 km almost certainly, but what about comparing 30 km to 150 km? Plug-in hybrids basically have two complete drivetrains in one car, which adds a lot of additional complexity, weight, and cost. A large enough battery will still be more expensive, but as battery prices come down the crossover point gets pushed up. I predict that eventually both plug-in hybrids and traditional hybrids will make no economic sense, and there will only remain ICEs and full EVs.