I think the main reason is that StarCraft sprites were based on 3d models so either they can be made higher definition by working from the original assets or they simply upscale better.

Wc1 and 2 mainly uses hand drawn pixel art sprites, and it looks like they have gone with the "crude upscale + retouch" approach. Makes them look like the super scale filters lots of people used on emulators back in the day.

Honestly I think original art and a solid crt filter is the way to go with old Pixel classics. But i know this is a divisive position.